Another big issue is the frequentity of global database from hgdgsvhgvuj's blog

It was upgraded and optimized for Diablo 2: Resurrected but remains stuck in 20th-century technology and has difficulty staying up to D2R Ladder Items date with "modern game play."

"In 2001 the year 2001, there wasn't much much content on the internet concerning learning how to play Diablo 2 'correctly' (Baal runs for XP pindleskin, Ancient Sewers/Ancient Sewers/etc magic finds, etc.)," PezRadar said. "Today however, a beginner can find the most amazing content creators who are able to teach them what to do in a variety of ways.

Many of them entail a lot of database load, in the form of creating load, then destroying games in quick succession. Although we knew this was possible--with players creating fresh characters on fresh servers, working hard to get their items of magic to find--we greatly underestimated the potential we got from beta testing."

Another big issue is the frequentity of global database saves which are happening way frequently without any good reason. Blizzard is making some tweaks to help smooth things out for now and is also looking to implement a more permanent fix, but it'll be some time away because it's "an structure overhaul that will require time to design and test before implementing."

For now, Blizzard is taking three steps to create Diablo 2: Resurrected more effectively accessible. Rate limit, which will put limits on how quickly and frequently players can make and join games; the creation of an MMO-style login queue to ensure servers won't be slowed down by D2R Items for sale large numbers of simultaneous logins. Also, breaking down essential functions into smaller functions.