Installed v3.7.1 on Windows 10 1803 and 16GB of RAM on a disk with 108GB free. Created mame64 database, imported data from mame64, database saved to a drive with 643GB free.
After 4550000 processed lines (really?) a "not enough memory" error occur.
P.S. After writing this, I discover this is the v4 issues site, but can't find de v3 site. If it is really only for v4, it would be good to indicate it in the information box of this page and also to give the link to the v3 site. I hope my sumission will be considered anyway.