Cache size and Seconds to preroll render

Cache size in Settings → Preferences, Performance tab is used to store images on the timeline. One 1080p frame uses about 10 MB. The default setting is 256 and this is enough for testing and running. However, why not use more memory if it is available. To experiment for testing a good number tuned to the way you use your computer, set the cache to 0, start up CINELERRA-GG, load a typical media file, play it and run top on the command line in another window to see how much memory is being used. In the top display, look at free memory. Whatever your computer is not using, is a good number to use for cache. If you start other programs, or change the design of the session so that it uses a lot of frame storage, you may need to experiment again later and resize accordingly. The system keeps all requested data cached until it is replaced by other data or you reboot your PC. Reboot if you want to clear the cache.

Seconds to preroll render in Settings → Preferences, Performance tab are used to increase the amount of frames (which are calculated in advance) at the time of their use. The default setting is 0.5 sec but you can increase it to 1.0 sec to improve smoothness in the timeline. Higher values are always less effective.