[clipper] Memory-related issues with xfade implementation

[lae]

Just reporting an issue another fansubber seems to be running into:

For me, it works if I try to clip up to two segments
More than that and memory skyrockets to the point of rendering my machine almost unusable
This could be a problem on my end, the logs don't seem to have anything strange but WARNING: library configuration mismatch, but it's been working until now with no problems
Tried adding things to the different commented lines, changing fonts, changing fade values but it's always the same result

example ffmpeg output from failing encode: https://cdn.discordapp.com/attachments/748914666415194143/787785171143360582/11_fades.log