If you find some slowdowns are noticeable, you can open bugreports about them. Then we can investigate.
There is little point in blindly benchmarking everything, I think.
However, comparing against BeOS isn’t exactly fair. We have antialiased fonts, GUI layout, and localization, and that’s just looking at the first level of what’s going on. Of course it’s going to be somewhat slower. In the case of localization, there is room for optimization, for example because we compute a hash for each string, and this can end up taking a noticeable time when there is a lot of text. We are also trying to load catalog string from various places (packaged/non-packaged, as resources in the executable or as standalone file, standalone file in data/catalogs or next to the application, and using various catalog formats that are loaded from add-ons (themselves loaded from various directories). This adds up to quite a lot of system calls and disk access before anything gets done.