What is the fastest way to level past 95 in Diablo II?

TLDR; Baal runs for weeks. Don't do it.

It's a slog, but Baal runs are the best way to level after patch 1.10. It used to be Hell Cow Level (if it even exists) pre 1.10. Some people do Chaos runs because it's more fun and they don't have to wait for Baal to summon his minions. There are bots on Battle.net that run both Baal and Chaos runs all day every day.

The time it takes to go to the other iLvl areas is not worth it, especially on battle.net, because your map will be random and you won't find it in a relatively short time. You're better off just teleporting to Baal.

If you are playing single player, teleporting to Pit and Tunnels IS worth it, because your map doesn't change.

Most people get to 90-95 and make a new character because it literally takes hundreds of hours and if you ever die, you just added another 30 hours because of the EXP loss.