Not sure if this happens to everyone, just checking. Yesterday I did two flights, KORD-KRDU and the return leg without shutting down and restarting the sim. 
 

On final to 28C I got to as low as 1FPS and the sim was pretty much unusable but I somehow managed to touch down and exit the runway. Not the first time this has happened to me. Is this normal behavior in the current state or is that me? 

I noticed by my fourth flight or so I was getting a lot of micro stuttering.  I’m on the SU12 beta and was starting multiple flights investigating an issue so it’s hard to say what the issue is.

I normally restart the sim for the return leg to avoid any issues, but I was in hurry yesterday. I miss the option from FSX/P3D to be able to go on with the return leg without exiting the sim or to the main menu. 

I've been noticing the manipulators thread steadily increasing on many of my flights. Since I disabled FSLTL and went back to stock live traffic it has gotten significantly better.

23 minutes ago, kiwikat said:

I've been noticing the manipulators thread steadily increasing on many of my flights. Since I disabled FSLTL and went back to stock live traffic it has gotten significantly better.

I turned off the FSLTL injector when it started acting up, but it didn’t solve the degradation. I don’t know how to check but potentially simconnect was still getting hammered with requests? 

When I do return legs in this sim without restarting it, I get similar performance degradation. Frames drop into single digits on approach on the second leg. Also similar, I turned off FSLTL injector and also saw no difference. Sort of discouraging but hopefully this gets addressed at some point.

3 hours ago, Drumcode said:

I normally restart the sim for the return leg to avoid any issues, but I was in hurry yesterday. I miss the option from FSX/P3D to be able to go on with the return leg without exiting the sim or to the main menu. 

Same here, except for a testing situation like today I always exit the sim on the rare occasions I have time for more than one leg in a row.

If often do two or three consecutive flights w/o shutting down MSFS and don't see significant degradation.  I have had the very rare scenario as described w/ ultra low frame rate but it is so rare as to not be worth trying to troubleshoot for.  I have paused a flight (Esc > Space) for several hours, returned and had substantial degradation, but often no problem with that.  

I’m going to try it again next weekend. Is there a way to see if the simconnect is getting bottlenecked somehow? 

Looks like a persistent memory leak issue with the sim. I gets drained when you fly multiple legs somehow.

Is this with the Beta ? or currant version? And if so, has it been reported?

I usually get the memory leak with traffic enabled, fps halves on multiple flights so have to restart after each flight. Think this has been known by ASOBO for a while now.

Is it an issue with 40 series cards? I do not have any performance degradation what so ever since SU10! I use Justflights FS Traffic set at 100% and haven't had a single drop.

13 hours ago, Car147 said:

Is this with the Beta ? or currant version? And if so, has it been reported?

Nah, SU11. I am going to try this with other scenery than FSDT's ORD too. It has happened to me 2 or three times and all on final to O'Hare. 

22 hours ago, Drumcode said:

I turned off the FSLTL injector when it started acting up, but it didn’t solve the degradation. I don’t know how to check but potentially simconnect was still getting hammered with requests? 

Turning off the injector won't help if it's the same problem I have seen. It has happened to me twice and both times is was FSLTL and both times it was because the were loads of planes all spawned on top of one another and stuck at one part of one taxiway somewhere at an airport. Turning off the injecter does nothing as they are all still there. I'm willing to bet this wouldn't happen with FSLTL turned off from the start.

I do connecting flights all day without restarting the sim and never have a problem when FSLTL isn't running and never saw it until I started using it a few weeks ago. Next time it happens have a good look around the airport with the drone where the planes are and see if you see the same problem.

Another thing I noted is that the both times it happened was when I flew from one airport to another and the next leg saw me fly back to the same airport. On return to the airport there was a load of planes all inside one another and performance just tanked. As I said, turning off the injecter didn't remove the planes. This is an FSLTL problem.