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Performance section

The main focus of the performance section is rendering parameters not available in the rendering dialog with the obvious gain of perhaps better performance. For more details about using GPU hardware acceleration for both decoding and encoding see Hardware video acceleration.

Cache size
  to speed up rendering, several assets are kept open simultaneously. This determines how many are kept open. A number too large may exhaust your memory rapidly. A number too small may result in slow playback as assets need to be reopened more frequently.
Cache Transition
  transitions can be slow on timeline playback. With this parameter (active by default) a cache is used to smooth the transition. You might see a slight hesitation at the beginning of a transition when memory is being loaded then quite often it will play at full speed.
Seconds to preroll renders
  some effects need a certain amount of time to settle in. Checking this option sets a number of seconds to render without writing to disk before the selected region is rendered. When using the render farm, you will sometimes need to preroll to get seamless transitions between the jobs. Every job in a render farm is prerolled by this value. This does not affect background rendering because background rendering uses a different preroll value.
Force single processor use
  CINELERRA-GG tries to use all processors on the system by default, but sometimes you will only want to use one processor, like in a render farm client. This forces only one processor to be used. The operating system usually uses the second processor for disk access. The value of this parameter is used in render farm clients.
Project SMP cpus
  to restrict the number of processors utilized, change the count number. This number will be used for the plugin per load balance operation cpu limit, which uses smp-cpus to stripe your data. It does not affect the number of cpus used in any other CINELERRA-GG operation besides plugins. On large cpu systems, it can come in handy to downgrade the number of cpus used for some plugins; otherwise it uses all of the processors and splits up the program into too many pieces which may add considerable overhead in high cpu count systems.
Use HW Device
  CINELERRA-GG can use hardware timeline acceleration (decoding) via GPUs thanks to the OpenGL video driver. By default the X11 video driver is used, which works only with the CPU. See Video Out section. For h264, h265 (HEVC) and VP9 codecs you can use libraries specific to AMD, Nvidia and Intel graphics cards. For AMD and Intel set vaapi; for Nvidia set vdpau (also works with AMD thanks to a wrapper). Cuda does not accelerate decoding with Nvidia, but it does allow some plugins to run that are not available otherwise. None (default) uses the video driver set in the Playback A/B tab.