I loaded the moby-dick-test-markdownfile into bear. It contains 212.000 words and 1.2 million characters. In comparison to obsidian and ulysses it needs much longer to load. Also the search is by far slower than in the other apps, never mind if global search or in-note-search.
Edit: Ulysses has seemingly the fastest search of all three apps but it needs same time for loading/importing the file as bear. Also I had success to let the ulysses app hang by searching for one letter only. I tested again quickly. Sorry for the misinformation in regard to that point