Did you just scaled down the server number from 4 to 1?

When the league starts, it's fast.

After a month, it's slower.

After two months and few patches, it's slog.

GGG devs are on record stating they don't care about long-term player retention, only league populations - specifically during the first 2 weeks of a league's launch.

If this current approach is unappealing to you, consider taking action that could trigger GGG's reevaluation - IE:stop playing Leagues, especially during the first 2 weeks of their launch. Play Standard instead.