might be relevant:
http://www.anandtech.com/show/6857/amd- ... dmap-fraps
after reading the article, it seems that AMD has problems with stuttering in games.. the stuttering begins when system resources aren't enough to render 60 FPS... (or enough to render fast enough that your wont notice stuttering)
Action seems to pull just enough power that stuttering in BF3 becomes visible for me...
The solution to the issue is two fold:
1. AMD needs to update their drivers to reduce stuttering in BF3 (DX 11 games - they are working on DX10 atm.)
2. Mirillis Action should work to reduce the amount of CPU / GPU cycles needed to grab video...
2. Mirillis should lower the CPU Priority from Normal to Below Normal
in my case - i think im experiencing stuttering because 2560x1440 is more demanding than 1920x1080 - and thus i experience stuttering because my hardware isn't fast enough

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Found a solution that seems to work
By lowering the CPU Priority from NORMAL to BELOW NORMAL for all 3 Action processes:
Action.exe *32
Action_x64.bin
Action_x86.bin*32
After doing this, i don't experience stuttering !!! YAY !
The video result is the same: 1080p30 .. no difference in any way.
i tested NORMAL and BELOW NORMAL - the video result is the same !!
WOOOP !
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Here is a script to make a BAT file, that sets the CPU Priority:
wmic process where name="Action.exe" CALL setpriority 16384
wmic process where name="Action_x64.bin" CALL setpriority 16384
wmic process where name="Action_x86.bin" CALL setpriority 16384