Base 57: I never use auto save.
 

emwhy: I have never changed my midi driver.
 

64 would be low enough to not cause this in my opinion. That is definitely disk buffer though (I think default is more like 256 or 512), not audio IO?

rodreb
bvideo: Don't we need that checked to be able to do punch ins?

If it is causing your lag and you always want to have every channel live for punch-ins, you'll be stuck with it. There are other ways to do punch-ins and the help file gives further help on optimizing "allow arm". But first, is that what is causing your problem?

I should have read your OP better sorry. Didn't look at what your were using for equipment.
 
For the heck of it, try a different USB port. In my machine before I returned my Focusrite, it would do the exact same thing when I hit play or stop. It was plugged into a USB 3.0 port that had an older VIA chipset on the MOBO. That was with the 4.15 driver which was their official release. I switched it to a pcie/usb card with a newer chipset from Fresco Logic and the start/stop issue went away with that driver.  I also know that Focusrite has a beta driver that some including myself here have used that cleared up many issues. It's version 4.26 on their beta site. The 4.26 driver worked with the older VIA ports on my system. Unfortunately I had other issues with the unit and had to return it, but I think the driver and usb port swap might solve your problem.
 
 
 
 

emwhy: It's not a USB unit, it's Firewire. I'm using a firewire card with a Texas Instruments chipset that is on Focusrite's approved list. As far as I know, I have their latest driver but, I will check again, though. Is it possible a firewire card could slowly die over time? This setup used to be fine.

Oops my bad.