Maybe you mean 2.2.x? It looks like that not only has an sqlite-page-cache option to replace needing an environment variable, but it also has large default, said to be 1% of system memory.
CommandLine help will probably show you the value. My help says 326 MB on a 32 GB system.
In another test, my large backup (about 1 TB) recreated in an hour on 2.1.2.0_beta_2025-08-20 which is far faster in this pre-2.2 Beta than it used to. I did use a 1 MB blocksize due to its size…
Backup destination is a portable USB drive. System is a quad-core desktop with old 2012 CPU.
I still wonder if you’re on 100 KB blocksize, but you haven’t looked and wouldn’t have known to enlarge it for larger backup anyway. My rough guess thought that default might hold to 100 GB.
Please change default blocksize to at least 1MB #4629
Blocksize should be at least 1MB – performance for larger backups falls off a cliff if blocksize is reduced below that level.
and I think a big part of the cliff is thrashing tiny 2 MB SQLite cache, then maybe OS cache next. Further performance improvements are in Canary, but didn’t catch 2.2, so might come out in 2.3.