I seem to have found a way to solve most of the meter slowness issues. Try switching to an external trigger and applying pulses (positive, 100-500uS length), frequency, for example, 15-20Hz, to the external trigger input. Switch on the continuity check mode and... you will not recognize your meter: the response will be instant and stable!
https://youtu.be/l6XR-P07voMI think most of the slowness problems are due to serious bugs in the internal trigger signal generation. It is constantly interrupted, this can be clearly seen on the oscilloscope in the continuity mode and other modes with fast synchronization.
It is also worth noting that the bar meter in the EasyDMM program works very quickly, as it should. And on the meter screen it is very slow, which is unacceptable!
There are also serious bugs in the "Trigger Delay" option in "Acquisition" screen. The sampling intervals do not correspond to the delay which setted and vary within 1 sec. If you set a delay of 1sec, then the real measurement interval will be 1.65 sec.
If you perform the same operations through the EasyDMM, then everything works correctly, because the trigger signal is most likely generated by a computer.
Everything above has been tested on SDM3065X, but I'm pretty sure it will work the same on 3055 and 3045X.
I believe that Siglent should solve this problem (unstable internal trigger generation) in the first place, this will greatly improved all aspects of working with the meter.
upd: the screenshot shows the "ragged" internal trigger signal in the "Continuity" mode