Running more than one process on a clip will impact the performance of the system. As the system runs it is expected for the processing to slow down some as the system heats up and VRAM is tasked.
Running the Video AI app is very different than normal video editing apps, as the AI models and processes are very memory intensive. The larger the video input resolution and the higher the frame rate the slower the processing will be as that is more pixel info for the model to read and interpret.
The dev team is constantly working to improve the processing speeds of the models and the app on all types of computer systems and work more efficiently.
Have you taken a look at the benchmark process page to compare results with other user setups?
If you would like to share your logs for review, you can do so here or send them directly to the support team at help@topazlabs.com for further review. There could be some settings that need to be tweaked or bottlenecks that can be resolved to help improve your performance.
How To Obtain Your System Profile (Mac)
To gather logs, please select Help > Logging > Get Logs for Support and attach the zip file to your reply.
