QTGMC slows down playback

[gispos]

I'm experiencing strange behavior with Avisynth 32-bit and QTGMC.

Without prefetching, I get 30 FPS, but if I then go back a few frames (about 30, frame by frame), I only get 13 FPS.
Either there's a memory leak or some other error that's slowing down subsequent playback.
With Avisynth 64-bit, the behavior is also noticeable, but not as pronounced.

With VDub2 32-bit, it's the same behavior, except you have to go back frame by frame two or three times before playback starts to stutter.
QTGMC or Avisynth, which is to blame? Or is this unavoidable?

Is this only happening to me?

[hello_hello]

I seem to be able to duplicate it in AvsPmod (only tried 32 bit).

I opened a (1080p) video I was working with and added the following to the script (no prefetch).

AssumeFPS(30000.0/1001.0)
CropResize(720,576, OutDAR=16.0/9.0)
QTGMC()
Trim(9000, 9999)

Playback speed was around 30fps.
I ran a FPS analysis, and even though the analysis doesn't display the final frame rate when AvsPmod is running in Wine for some reason, it did show me it was wandering around 30fps and took 35 seconds to complete. After playing a bit of the video and stepping backwards 30 or 40 frames, then doing it again, the next FPS analysis showed around 12fps and took 82 seconds to complete, and playback speed was the same.

I don't understand why the FPS analysis changes as well, but I only needed to remove QTGMC from the script and play a bit of the video to reset the speed when I added QTGMC again.

[gispos]

At least I'm not the only one.

This behavior doesn't occur when reverting in larger increments, only when reverting frame by frame.
With 64-bit, I get ~34 FPS, and after reverting in frame increments (30 or so), it drops to 22 FPS and can only be fixed by a script refresh (F5).

[real.finder]

maybe some filter/dll in QTGMC dont like going back in frames