I this there is a good chance that this is the problem. I think that some antivirus programs “learn” over time that if you use something multiple times it will stop checking it so often. Sometimes you can go into the settings to “whitelist” an application. In addition to whitelisting Shotcut, it is also good to whitelist “melt” the export program.
Also, see this issue with Grammarly:
So there could be other things on the computer that affect it.