I upgraded my system recently from Windows 7 to Windows 10 and started having problems with Flash Player videos freezing or stuttering. The audio would continue to play normally, but the video would freeze for a second and then start again. This would happen repeatedly throughout a video, with some sites being worse than others. After many days of searching and trying different things, I finally got it fixed.
One of the things I found while searching for a solution was this thread on Adobe’s forum going back to 2013, titled "Flash player stutters for 1 second then continues normally."
There are 6 pages of posts with many people experiencing the same problem. In June 2015 a helpful Adobe moderator locked the thread with no official solution to the problem. There’s an open bug with a Status/Reason of "CannotReproduce."
On page 5 somebody suggests enabling HPET in BIOS and setting a "useplatformclock" boot entry option.
HPET stands for "High Precision Event Timer."
I checked my motherboard BIOS, but couldn’t find any HPET settings. Still, I set the "useplatformclock" setting, rebooted, and tested Flash Player. Success! No more Flash Player video freezing!
Here’s some light background reading that seems to be related to the issue (though Flash Player isn’t mentioned).
So this is what I did to enable the HPET and fix Flash Player.
To set "useplatformclock" I used the bcdedit command, from a command prompt run as Administrator.
I checked the existing settings.
I didn’t see any preexisting entry for "useplatformclock."
Then I set it to "true."
bcdedit /set useplatformclock true
I rebooted the system, as it needs to be rebooted before the setting will take effect, and checked that the setting was still there using the "bcdedit /enum" command like before (it was).
Then I tested some Flash Player videos. They played properly without freezing.
This is the command to delete the setting.
bcdedit /deletevalue useplatformclock
I actually deleted the setting, rebooted, and tested some Flash Player videos again to verify they would freeze when the setting was reverted. They froze as expected. I put the setting back, rebooted, and it was good again.
Later, I found this utility, Harmonic, that checks the status of the HPET.
www.bytemedev.com/programs/harmonic-help (Note: Original link no longer resolves, new link is from web.archive.org)
This was useful to confirm that the setting was already enabled in the BIOS (System Using HR). There is also a button in the utility to enable/disable the HPET, though I didn’t use it (I used bcdedit instead). Here’s a screenshot of the utility before and after the change on my system.
So far I haven’t noticed any differences in my system, except that Flash Player works now.
I’m not sure what it is about my system that causes this issue in the first place; perhaps something with the cpu/motherboard/chipset. I also don’t know if this would help anybody else. These are my system specs, for reference.
NOTE: I’ve had to redo the "useplatformclock" setting several times now, after major Windows updates. It seems the update sometimes wipes out the change, so it’s a good idea to check if it’s still there after big updates.