> Higher system load for what? USB or TB? It's not clear to me the way you put it.
ASIO buffer size can not be 32 buffers for all types of project.
If you use a higher sample rate you need bigger buffers.
If your CPU is under stress (by big project or one with CPU hungry VSTs) you also need bigger buffers.
All is about whether the CPU does it get managed to perform the i/o tasks in time.
For this reason many people tune their PC so that the CPU cores are not doing useless stuff.
This gives the CPU cores more headroom to be able to process all in time without audio loss.
The USB protocol usually is know to have more overhead compared to PCIe.
So if you have a high Project / CPU load on your system then it it could be,
that you require with thunderbolt only an ASIO buffersize of 128 buffers,
where you might require with USB3 maybe 256 ASIO buffers.
Thunderbolt has PCIe speed.
From the pure latency values between USB3 and Thunderbolt you dont see significant latency difference.
But under a heavily loaded systems its much likely (never tested it on my own), that Thunderbolt
works more efficient so that you can works potentially with lower ASIO buffer sizes.
And if you can use lower ASIO buffer sizes, then you have less latency end-to-end between
Recording interface and DAW on your PC ...
In such discussions btw always carefull .. LatencyMOn i.e. measures another latency than
the latency which is being reported by the RME driver to Cubase.
There is also a latency inside of Windows inside of the kernel, how agile the CPU can react / work
on the processes and threads. If there are i.e. drivers that occupy the CPU for too long and if
on this core/thread also an audio process is running, then this narrows the ability of the CPU
to process audio in time (without loss, clicks, pops), especially if the system is under stress.
This you can only resolve by tuning your system and by using higher ASIO buffer sizes.
And thunderbolt shall have the benefit - as it equal PCIe performance - to perform better
in higher load szenarios compared to USB. Although I could not see this big difference in my projects.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13