A new update for everyone 10.15+ (If you have an older OS you can try this version, but let us know if it doesn’t work for you).
If you are using 10.14 and older, you’ll want to use the legacy version fo VDMX b8.7.2.4
More details about VDMX versions in the wiki doc: https://docs.vidvox.net/vdmx_versions.html
Can you post a screen capture of what you mean by these corrections? And possibly share your project?
By speed do you mean frames per second? FPS?
Could you post your system specs? Newer machines should run faster (in theory).
Please make sure you are not using AV1 codecs that are not officially supported by Macs. (They can be .mp4 similar to HEVC, H.264, and H.265, but do not perform well on unsupported systems).