Replying here to CONFIRM I have the same issue as Antonin 2020. I was building my city and all was well until I set up my metro networkat around 60K inhabitants (I was doing an American build so my city is very car centric). Not for nothing, but I have a pretty good gaming computer so everything was still buttery smooth.

I set up my metro network using a variety of underground stops, including two with multiple tracks but mostly vanilla stations. My simulation slowed to a crawl. My FPS was fine - my GPU is handling anything I throw at it. But the simulation itself was barely chugging along, and I have one of the best single-thread processors out there. It was so bad that x1 and x3 speeds were indistinguishable, and even on x1 speed I could see the simulation slowing down via the cars and pedestrians slowing down every second to let my CPU catch up. It was like a pulse - a second of slowed simulation, a second of normal simulation, back and forth. I also noticed I randomly got "Not enough Customer" complaints from my commercial zones completely out of nowhere, even though I hadn't expanded my commercial in some time and had added considerable residential. At first I thought this was unrelated.

I thought it might be TM:PE or Real Time since I know that is CPU heavy, but I reduced the simulation accuracy and dynamic lane changing settings to no avail. Unsubbing from that didn't help either. I then disabled Real Time. Again, no change. Unsubbing from both also made no difference.

But I hit "Reset all stuck citizens and vehicles" under Options>:TM:PE>Maintenance on a whim and the simulation sped right back up to normal. But the speed only lasted for about five minutes and it came right back. I then noticed an option under TM:PE to "show pathfinding stats". I enabled that which shows how many paths the simulation is finding at a given time.

My god, at any given moment there were between 1 and 2 thousand paths the pathfinder engine was computing, and it was oscillating up and down. It timed *perfectly* with the simulation speed seemingly pulsing as described above - whenever it slowed down, the pathfind count was at ~2000, and whenever it sped back up for a second, it was dropping back down. It was like a fast sine wave.

I again hit "reset all stuck citizens and vehicles" and the pathfind count plummeted to less than ten and simuation sped back up. Clearly, I had stuck vehicles or pedestrians somewhere and the CPU was working overtime to constantly get them "unstuck" but was failing over and over. Using the option in TM:PE to reset all traffic did nothing, so I knew I had pedestrians stuck somewhere. I had no ped paths in my city, nor any bike lanes (I know they can sometimes led to cims getting stuck as well).

So it had to be an issue with by Public Transport network. But I only had metro stations - no buses, no trams, no nothing! I deleted my metro network and the problem instantly resolved itself - the pathfinding count dropped to normal and my simulation sped back up to normal.

On a hunch, I rebuilt my metro network station by station and watched the pathfinding count on x3 speed for a about five minutes or so after each station. The *moment* I placed a multi-track station via MOM, the count started climbing, cims started getting stuck somewhere and the simulation would start to slow down again.

I then rebuilt the metro network using only underground, single track stations, placing multiple ones close together at transfer points. No pathfinding issues, stuck cims, or slowed simulation speeds ever returned after twenty minutes.

It does appear that cims have a tendency to get stuck in metro stations with multiple tracks for eternity. This also is what caused my "not enough customers" complaints - cims who were going shopping would get stuck, and they would never make it to the commercial zones. The moment I resolved the problem - either by resetting stuck cims, rebuilding the metro with only single-track stations, or demolishing it entirely, the complaints from my commercial zones disappeared shortly thereafter (I tested multiple times).

The only solution I can think of is to not to use multi-track metro stations. FWIW, I haven't tested with overground MOM metro stations, but I did try overground multi-track rail stations and had no issues there.

The only mods I have that directly affects pathfinding AI is TM:PE. I also have Real Time as mentioned which affects pathfinding indirectly (since cims have a routine).

I really hope the mod developers see this and can recreate it so they can fix it. I LOVE the mod and what it does, but until the pathfinding issues get resolved I'm reticent to use it to its fullest potential.

@truemanmontfort thank you so much, seriously!! you saved me so much time and money... was considering upgrading the CPU and everything in order to make this work since my game was barely even crawling. So glad I found your comment.

when I checked the pathfinding stats... lmao... it was in the 9000s, consistently...

now that I've replaced everything with standard vanilla 2 track stations, and just made separate tracks/stations/lines for the express trains, pathfinding is literally at ZERO, consistently

I was amazed. still am, had to come back here and say it, so truemanmontfort if you see this I salute you