Memory usage is a potential concern for CBR due to the lack of specific memory limits for the planning stage. I only have anecdotal observations from doing the original CBR performance analysis, but I noticed a few cases where peakTrackedMemBytes (recorded in the explain output) was quite a bit higher in automaticCE mode than in the baseline

It might be relatively simple to add memory usage as a new metric for the synthetic benchmarks just by comparing that field to get some sense of CBR's impact on it.