High CPU load when digits on Side Panel are running

[jpka-]

There is unusually high CPU load when 1) Side panel is shown (Ctrl+P), 2) Transport tab selected, and 3) Transport is rolling. It gives visible and running Frame, Time, BBT digital scales. It consumes as much as 19 to 21% of i3-8100, and ~47% of Celeron J4005 (with fastest possible RAM at both cases; no extra GPU). Rack is empty.
When i comment out these two lines:

/usr/share/carla/carla_host.py
L2217: self.ui.l_transport_frame.setText("%03i'%03i'%03i" % (frame3, frame2, frame1))
L2222: self.ui.l_transport_bbt.setText("%03i|%02i|%04i" % (bar, beat, tick))

then CPU load drops quite substantially. Looks like setText() is far not efficient for fast updates. Carla 2.5.9, but same is with 2.5.8, and with as old as 2.4.2.
It can be non noticeable on higher horsepower CPUs, though.