Major multithreading optimzations
In 1.11 the game simulation and the game UI can now run fully independent from each other. This boosts the game simulation speed by potentially a large margin, depending on how large your save is (and for users with less powerful GPUs, on how complex your on-screen buildup is). Since the game simulation was already massively parallel, this increases the CPU usage of the game. Faster sim = more CPU usage. If you prefer the game making less use of your CPU, in 1.11 it is also possible to limit this capability down to just 2 sim threads, with the corresponding sim performance hit.
New pax pathfind capabilities
Board only and disembark only line stops are now possible. Although not super realistic, it is useful to keep local pax from boarding long distance lines making multiple stops in a large city, for example. Or to make sure large capacity lines only empty their trains in some selected, less busy stations. Factorio or a human transit simulation? You decide!
Pax pathfinding can now consider a pax staying inside a train for more than 2 train runs. This limit has been in the game since 1.5 and it is now finally removed. The pax pathfinder can now plan a path leg which keeps the pax inside the train until the train starts a technical line or an already visited station appears (not just the boarding station), whichever comes first, over any amount of train runs, including an entire week worth of them.
"Figure 8" or "pretzel" shape lines are now better supported. These lines, in conjunction with single line stations, have had limited support in the pax pathfinder. In 1.11 the game is able to detect more cases of a transfer station, including cases of a line crossing over itself on the same station, or a common looking line having a single direction loop in one end (in this case, the station(s) just before the loop are marked as transfer). This means there are now some cases where pax can disembark in a station and pick a train of the same line, to avoid the loop part of a "figure 8" line for example.
Multiplayer fixes
I've written this a bunch of times over the years already, but the new version contains major multiplayer fixes and optimzations. This time I'm confident enough that I've enabled up to 100x shared sim speed and made it the default setting (famous last words?). If you are a multiplayer fan give the beta a test.
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For a more detailed and technical look into what's in 1.11, check the devblogs:
https://carloscarrasco.com/nimby-rails-november-2023/
https://carloscarrasco.com/nimby-rails-december-2023/