Instead of dumping 100 clips on a single timeline, consider creating 100 timelines instead.
- For your stretching from 240 fps to 30 fps, use the Interpret Footage function in the Project window (select all clips of 240 fps > right-click > interpret footage > set to 30 fps)
- On first timeline, add your clip, do your processing
- Go to project window, duplicate the sequence (CTRL/CMD+SHIFT+D)
- Rename duplicate sequence
- Open up duplicate sequence > replace clip with new clip
- Repeat 98 times
- Select all sequences in Project window > right-click > Export media
Hope this helps.