If clips are truly being sped up by 10,000 then that's heavy-duty work. Pre-produce original (not low-res) clips, sped up individually. Then export each. Bring them back in as clips, then add your song. That way, the clips will little tax your system.
After completing several songs, exporting those then starting a new session containing only intermediate exports may be an option. Whether this is a valid approach for you depends upon how you mate the song to the video and how you envision its final form.
In lieu of a single completed video, the project may have to be broken up into multiple exports, each containing several earlier exports of completed videos.