I have only imported a few Sketch-Up files, mostly whole building shells. I used the Merge import method for those. The resulting ‘object’ looks great and seem fairly small in poly count. However, I prefer not to use them for precision modeling work, only general visualization.
For interior objects, I try to find well-made objects and sometimes convert them. In cases of items with high poly counts (e.g., furnishings and equipment), I prefer to create those items anew in AC using the morph tool. Then they are native with fewer polys.
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AC26 USA on 16” 2019 MBP (2.4GHz i9 8-Core, 32GB DDR4, AMD Radeon Pro 5500M 8G GDDR5, 500GB SSD, T3s, Trackpad use) running Ventura OS + extended w/ (2) 32" ASUS ProArt PAU32C (4K) Monitors