There is substantially less of that with Twixtor 4.5 then previous versions on cluttered multiple motion scenes, but it can still happen, it is typically caused by large regions that are visible in one frame and not the other, in which case the documentation goes over in detail about how to try to fix that with Twixtor Pro and a bit of manual work. The amount of “PRO” features varies per app we support currently, so I won’t be more specific.
If you are speeding up, you might consider Nearest Frame mode to reduce that effect
Pierre
RE:Vision Effects