Just for reference: using my freshly build KICAD 6.0.7 on mint 21 “Vanessa” I loaded the named reference OLINUXINO/HARDWARE/A64-OLinuXino at master · OLIMEX/OLINUXINO · GitHub.
After removing the copper areas it took about 12 seconds to rebuild them again.
(AMD A10-7850K Radeon R7, 12 Compute Cores 4C+8G × 2, 16 GB RAM).