I've been using this for a few years now without issue, but now when I go to Sync>Mirror, it's so entirely slow for some reason, less than 2 MB/s, and I can't figure it out.
I downgraded a couple versions but it doesn't seem to change the issue, and nothing in my system has changed. I tried different usb ports with no change.
I use Samsung T7 drives and the transfers used to start fast right away, but now they just trickle across for about 10 minutes until it reaches around 400MB, then it'll start copying at max speed, (which on my system is around 400MB/s).
What do you think may have happened to reduce the initial speed so drastically? All I've been doing is upgrading the app when one comes in. It's unrealistic that all 3 of my Samsung T7s started going bad at the exact same time. They're storage/redundancy only, so once I copy stuff to them, they're disconnected and put away.
Windows 10
Massive copy speed reduction issue.
- Posts: 6
- Joined: 2 Jul 2025
- Posts: 6
- Joined: 2 Jul 2025
Any ideas on this. Issue persists even after 14.4 update. Currently replacing a 2.1GB file with a 6.2GB one, at a whopping +/-1.91 MB/sec, where it used to just copy over no matter how much I was copying or syncing in a matter of seconds.
Total time taken for one 2.1GB file to be deleted and be replaced with a 6.2GB file is roughly 50 minutes. What happened, and how do I fix this?
Am I the only one having this issue, and do I just have to keep having this issue indefinitely? Nothing changed, at all, on my system, between the time before and the time after this started.
Same drives being used, (all test the same good health and barely used as they ever have), same ports, (although testing all of the ports I have offers the same result), same everything, but the app itself now does its job at the slowest speed imaginable, for apparently no reason, still.
I really miss when it performed its function as intended, instead of this. I have other things I would like to do besides waiting for ONE file to copy over. I have to do this twice, by the way, so almost 2 entire hours wasted waiting for something that used to be over in a matter of seconds.
Is there any resolution to this?
Total time taken for one 2.1GB file to be deleted and be replaced with a 6.2GB file is roughly 50 minutes. What happened, and how do I fix this?
Am I the only one having this issue, and do I just have to keep having this issue indefinitely? Nothing changed, at all, on my system, between the time before and the time after this started.
Same drives being used, (all test the same good health and barely used as they ever have), same ports, (although testing all of the ports I have offers the same result), same everything, but the app itself now does its job at the slowest speed imaginable, for apparently no reason, still.
I really miss when it performed its function as intended, instead of this. I have other things I would like to do besides waiting for ONE file to copy over. I have to do this twice, by the way, so almost 2 entire hours wasted waiting for something that used to be over in a matter of seconds.
Is there any resolution to this?
- Posts: 6
- Joined: 2 Jul 2025
Wanted to post my solution to this issue.
Somehow, one of the updates earlier in the summer borked the program and restricted it speed to just under 2 MB/sec, obviously crippling it's usage for me.
I used Revo Uninstaller to get rid of any trace of FreeFileSync, reinstalled in from the most recent package, 14.4 at time of writing, and am presently copying everything back over to the drive that I had to format because of a corrupted .tmp file created by FreeFileSync that refused to delete, or allow it to even run. Working as intended now.
So Revo Uninstaller to remove all traces, then reinstall with latest version, in case anyone else ever runs into a similar situation.
Somehow, one of the updates earlier in the summer borked the program and restricted it speed to just under 2 MB/sec, obviously crippling it's usage for me.
I used Revo Uninstaller to get rid of any trace of FreeFileSync, reinstalled in from the most recent package, 14.4 at time of writing, and am presently copying everything back over to the drive that I had to format because of a corrupted .tmp file created by FreeFileSync that refused to delete, or allow it to even run. Working as intended now.
So Revo Uninstaller to remove all traces, then reinstall with latest version, in case anyone else ever runs into a similar situation.
- Posts: 4933
- Joined: 11 Jun 2019
The reformat likely fixed it, not the FFS cleanup and reinstall
- Posts: 6
- Joined: 2 Jul 2025
The need to format arose from the temp file that FFS placed on that particular drive that locked during a failed sync, that I could not delete from that drive and FFS refused to sync to again. All 3 drives I use for this process are virtually new, and have no errors, and nothing in my setup has changed.
I just updated to 14.5 and experienced the same exact slowdown, for whatever reason it's actually happening.
Revo and going back to 14.4 seems to have resolved it though, I just don't know why.
I just updated to 14.5 and experienced the same exact slowdown, for whatever reason it's actually happening.
Revo and going back to 14.4 seems to have resolved it though, I just don't know why.
- Posts: 2
- Joined: 16 Oct 2025
Ugh, reading these posts really makes me frustrated because I'm having the same issue, and don't have time to start sifting around temp files and such. Instead I just wait here and let it take overnight to sync something that should take 1/2 hour tops.
I just did a diff sync, and it took literally 6 minutes to copy 70 MB of data through my super fast wifi.
I just did a diff sync, and it took literally 6 minutes to copy 70 MB of data through my super fast wifi.
- Posts: 6
- Joined: 2 Jul 2025
It does suck that you're also having this problem, but nice knowing I'm not the only one.
Maybe if more than just myself is experiencing this slowdown for whatever reason it's happening, someone will be more prone to offer some type of actual assistance, instead of only saying it's not the app and leaving us to wondering what it could be.
No reason I should have to format a drive with about 1.5 TB on it just to get this program to act properly. Never had an issue with it, until I did. Unfortunate too, because it used to do exactly what I needed, in a very timely manner.
All 3 of my drives tested exactly how they should, for being Samsung T7 SSDs, and my USB ports also tested as they should. My slowest is around 330 MB/sec, and that's the speed that it used to copy at, until it decided it wanted to copy at or below 2 MB/sec instead.
Maybe if more than just myself is experiencing this slowdown for whatever reason it's happening, someone will be more prone to offer some type of actual assistance, instead of only saying it's not the app and leaving us to wondering what it could be.
No reason I should have to format a drive with about 1.5 TB on it just to get this program to act properly. Never had an issue with it, until I did. Unfortunate too, because it used to do exactly what I needed, in a very timely manner.
All 3 of my drives tested exactly how they should, for being Samsung T7 SSDs, and my USB ports also tested as they should. My slowest is around 330 MB/sec, and that's the speed that it used to copy at, until it decided it wanted to copy at or below 2 MB/sec instead.
- Posts: 2
- Joined: 16 Oct 2025
To be fair I'm noticing just copying files into a shared drive is also not particularly fast, even though internet speed tests from all these machines (all on wifi) is exceedingly good.
I will say that the shared drive is off of a Windows desktop (not terribly old, and it is relatively high spec) but it is a wifi USB dongle thing, vs a built-in.
The systems I'm copying from are Macs (all modern specs - a 2021 and 2024 model - and newest OS and FreeFileSync software).
I double-checked for security software (removed the McAfee I wasn't using on the desktop, some corporate security stuff on the 2024, but nothing by Mac defaults on the recently reformatted 2021).
I also tried what another user mentioned somewhere else, which is disabling IPv6, but also found many articles saying that's old news and no longer relevant with modern hardware.
The wifi router is a new model provided by AT&T and we have fiber, and I'm getting speedtest runs of 350 Mbps on the Macs, but noticing slower 30 Mbps on the PC, so now I'm like... oh, maybe something going on there. :facepalm: Gonna play with that now.
I will say that the shared drive is off of a Windows desktop (not terribly old, and it is relatively high spec) but it is a wifi USB dongle thing, vs a built-in.
The systems I'm copying from are Macs (all modern specs - a 2021 and 2024 model - and newest OS and FreeFileSync software).
I double-checked for security software (removed the McAfee I wasn't using on the desktop, some corporate security stuff on the 2024, but nothing by Mac defaults on the recently reformatted 2021).
I also tried what another user mentioned somewhere else, which is disabling IPv6, but also found many articles saying that's old news and no longer relevant with modern hardware.
The wifi router is a new model provided by AT&T and we have fiber, and I'm getting speedtest runs of 350 Mbps on the Macs, but noticing slower 30 Mbps on the PC, so now I'm like... oh, maybe something going on there. :facepalm: Gonna play with that now.
- Posts: 4933
- Joined: 11 Jun 2019
USB WIFI dongles are typically atrocious, as you saw in your tests as well.
"Maybe...someone will be more prone to offer some type of actual assistance, instead of only saying it's not the app and leaving us to wondering what it could be."
This is because FFS has rarely, if ever, been the root issue for slow performance. The unfortunate reality of tech support is no one can diagnose an environment they aren't in and you're the only one in your environment ¯\_(ツ)_/¯
All of your experienced behaviors points to a filesystem or hardware issue, which is why it was fixed after a format. Might be worth checking the SMART health of the device also, it could cause an issue again.
"Maybe...someone will be more prone to offer some type of actual assistance, instead of only saying it's not the app and leaving us to wondering what it could be."
This is because FFS has rarely, if ever, been the root issue for slow performance. The unfortunate reality of tech support is no one can diagnose an environment they aren't in and you're the only one in your environment ¯\_(ツ)_/¯
All of your experienced behaviors points to a filesystem or hardware issue, which is why it was fixed after a format. Might be worth checking the SMART health of the device also, it could cause an issue again.
- Posts: 6
- Joined: 2 Jul 2025
Funny how I've stated, a couple times now, that everything has tested working the same as it always has. It's all the same as it was before whatever this problem is happened.
Also, what seems to have been missed, is that the reason I needed to format that drive in the first place was that the temp file that FFS uses, somehow errored to the point that FFS would not attempt to copy to the drive anymore, or even bother deleting it's own temp file to start over, nor would windows allow me to delete the file. I had no choice but format the drive in that instance, (or figure out how to take possession of the file and delete it that way). That temp file was from no other program or process other than FFS.
It just so happened to seem to fix the problem, if only between those two drives, for now. I barely need to mirror those two drives, so have no idea if it's still acting fine, or slow again. The program itself doesn't offer any way for me to diagnose what it's problem could be either, as far as I know.
What I mean by my comment about actual assistance is the fact that almost any other company or creator can, and does, offer basic troubleshooting steps in the form of either settings to check, specific diagnostics to run, or even other programs to check to see information that could lead to finding the solution, and none of those companies or individuals seem to need to be in my environment to offer fixes that do indeed fix problems. It's pretty obvious that we're the only ones in our environments, that was never brought into question.
Just stating that rarely has FFS ever been the problem, by no means states that it never can or will be. I've checked everything, over and over, (yes, even my SMART), and absolutely nothing is telling me that anything is wrong. That's why I'm seeking assistance, because I can not find anything on my end that would cause something like this.
As far as I can tell you, everything involved with file transfers on my system, from the drives themselves, to the USB ports, the protocols, the file system, it's ability to copy to and from each of these drives... is all fine.
Windows can copy to and from all of these drives at the very least around 330 MB/sec, so what caused FFS to all of a sudden decided it was going to limit the copy/mirror speed to at most 2 MB/sec? What WOULD cause it to do this? Those are the questions.
I probably won't reply to this anymore past this, simply because it's not really affording assistance. Constantly being told it HAS to be us somehow, and not offering a way to definitively see whether it truly is or not, just kinda leaves us in the same position we were in before we asked. Shame too, because this program used to do exactly what I needed it to do in an actual timely manner, without problems. It still does it's copy/mirror, but sitting around waiting for files to copy like it's the late 90s, on modern equipment, is a bit ridiculous.
Also, what seems to have been missed, is that the reason I needed to format that drive in the first place was that the temp file that FFS uses, somehow errored to the point that FFS would not attempt to copy to the drive anymore, or even bother deleting it's own temp file to start over, nor would windows allow me to delete the file. I had no choice but format the drive in that instance, (or figure out how to take possession of the file and delete it that way). That temp file was from no other program or process other than FFS.
It just so happened to seem to fix the problem, if only between those two drives, for now. I barely need to mirror those two drives, so have no idea if it's still acting fine, or slow again. The program itself doesn't offer any way for me to diagnose what it's problem could be either, as far as I know.
What I mean by my comment about actual assistance is the fact that almost any other company or creator can, and does, offer basic troubleshooting steps in the form of either settings to check, specific diagnostics to run, or even other programs to check to see information that could lead to finding the solution, and none of those companies or individuals seem to need to be in my environment to offer fixes that do indeed fix problems. It's pretty obvious that we're the only ones in our environments, that was never brought into question.
Just stating that rarely has FFS ever been the problem, by no means states that it never can or will be. I've checked everything, over and over, (yes, even my SMART), and absolutely nothing is telling me that anything is wrong. That's why I'm seeking assistance, because I can not find anything on my end that would cause something like this.
As far as I can tell you, everything involved with file transfers on my system, from the drives themselves, to the USB ports, the protocols, the file system, it's ability to copy to and from each of these drives... is all fine.
Windows can copy to and from all of these drives at the very least around 330 MB/sec, so what caused FFS to all of a sudden decided it was going to limit the copy/mirror speed to at most 2 MB/sec? What WOULD cause it to do this? Those are the questions.
I probably won't reply to this anymore past this, simply because it's not really affording assistance. Constantly being told it HAS to be us somehow, and not offering a way to definitively see whether it truly is or not, just kinda leaves us in the same position we were in before we asked. Shame too, because this program used to do exactly what I needed it to do in an actual timely manner, without problems. It still does it's copy/mirror, but sitting around waiting for files to copy like it's the late 90s, on modern equipment, is a bit ridiculous.
