Yes, this could work for some processes, but it is difficult to generalize this solution.
For example, the splits would need to overlap by several seconds, else some discontinuity would appear at the junctions (depending on the plugin). Then, the X generated files would then need to be xfaded/combined (hence you need a very fast drive, too).
Then, there would need to be as many plugin instances as splits, and for memory-hungry plugins such as Izotope ones, or those that rely on hardware DSP, this could be an issue.
Also, this method can’t work with lossy formats such as mp3 and aac.
So, yes possible by principle, but not without potential glitches. Is that worth the effort, maybe I don’t know.
As a side note, I think WaveLab 11.1 will come with an update after the summer, with some added performances for certain processes (in the Global Analysis process, this is the True Peak detection that causes the performance loss at this time).