I’ve been using blenders VSE for editing for years, and, as a result of attempting more complicated caption styles and animations, I’ve discovered an oversight in the code that literally breaks blender.
To replicate this, make a ton of text strips with glow effects and put them in a metastrip. Then copy this metastrip a ton. Now, even if the cursor is not currently over the strips or they are hidden, it will struggle to function. You can even hide preview and it will still sit at like 4fps.
I think what is going on here is blender processes ALL METASTRIPS, for every frame, even if the metastrip isn’t visible on the frame or is hidden.
Please share this problem so we can get it patched, this is one of the only things limiting blender as a video editor.