Editing slow when other than first audio track is selected in long mkv video

What is your operating system?
Windows 10

What is your Shotcut version (see Help > About Shotcut)?

Can you repeat the problem? If so, what are the steps?
Have a long (e.g. 8 hours, although 2 hours into the video the effect is already obvious as well) video in the mkv container format and multiple audio tracks. The source player works fine, it plays the video immediately, even after changing audio tracks, anywhere in the video.

However adding a part of the video to the timeline when anything other than the first audio track is selected causes the player to wait for a while before playing the video on the timeline. The same happens after splitting a clip and playing the left side of the split or changing audio tracks to something other than the first one.

The further into the video the timeline clip is from, the longer the wait (from barely noticeable to 45s near the end of the video), so it seems like something is reading data from the start of the video file up until the added clip. Taskmanager shows relatively low CPU but very high disk activity during the wait time.

I turned off “Show Audio Waveforms” in the Timline settings but it didn’t help.

It doesn’t happen with the same video but converted into mp4 container format using FFmpeg (with -c copy).

Now that I know this I can just convert it, so I’m not sure I personally need a fix, but when you’ve already started editing and didn’t notice the issue at the start, but then it just gets worse and worse into the video and you have to wait half a minute after every split clip, it’s a bit irritating, so a fix or warning would be nice.