Shotcut preview playback is choppy for AVCHD

Even with my source material put on an SSD, the playback of AVCHD (.MTS container) video within the Shotcut preview Window is jumpy and stutters, dropping most of the frames. Why is it like that? I can play the video files smoothly in VLC. I don’t think my AVC .MP4 files are affected.

I find once you start adding filters things can get choppy. MTS from my Panasonic are fine until I start using filters, this is normal unless you have a super high performance PC or an editor which can create optimized media for editing (such as DaVinci Resolve).
However, MTS is not an ‘editing’ format, it’s a ‘camera recording’ format. Best to transcode to ProRes (for example) for editing.

I use Shotcut to transcode the clips I want to use and then use Hitfilm Express after that. I don’t want to transcode each entire video to minimise disk space consumption.