Size, Position and Rotate filter is very laggy

[shotcut]

First of all, Shotcut is generally laggy and people complain about it so frequently I usually simply no longer respond to posts about it.
Now, for the new version 20.10.31 release notes

Improved image quality when using Size, Position & Rotate .

That can make it slower. It also depends on Settings > Interpolation. I am not going to reverse that change. The image quality is more important. The usual remedy (as mentioned in the FAQ) is to use

Proxy Editing

Introduction Proxy editing is the process of creating and using low resolution videos and images in places of the original or optimized (Convert to Edit-friendly) files. This provides the advantage that your computer has less work to do in realtime while editing: decoding, scaling, and effects. This is, quite simply, because there are less pixels to compute. Then, when you are ready to export, it will use the original (or optimized) files for full quality. Performance is optimal when the pre…