I just got mine sync and its 660GB .... done in 5 days with a 3MBPS line on my phone data.
Just 16gb amd ryzen 9 7950 and 1tb ssd ext drive.

Yea, i did set the cache to 1800MB compare to originally 450MB. It does help. Even on my raspberry pi 5, i did sync it within 5 days on the same ext drive.

same core version 27.0. I think it could be the cache 450MB default setting. Try changing it and trying different setting. Hope it helps.