I tried loading a model with a large number of polygons - it really made blender 2.81 crawl.
6.4 million-triangle 3D scan of the Bust of Nefertiti. aem_aem21300_3dsl01_mo08-03_p.obj from https://www.thingiverse.com/thing:3974391
Maya on the same PC handles it without problems. (Ryzen 3700x /32 GB RAM/ Geforce RTX2600 / NVMe SSD / Windows10 )
Am I missing a blender setting perhaps ?