If the current version is the one causing the problem on your computer, try an older version. There have been a few reports from some users of performance issues.
So without more information about what system you have and what version you are using now, I can only advise you to download the version you were using before February.
You don’t even have to install it. You can download the portable version. Then just unzip and click on Shotcut.exe.
Additionally I assume you are using the proxy functionality and preview scaling. If not, read this first:
