sdr tlevision transmit has high CPU load

[dk1ri]

Hin
I have a Win10 corei7-6700 (2016) laptop with pluto (latest firmware) used for QO100 only.

Console version: 3.4 April 21 25
SDRtelevision version: April 23 25
OBS version 31.0.3

Additionally to these programs I need a webserver (XAMPP), firefox and a terminal to control the QO100 rig and TV transmit program for test.

SDRConsole works ok
SDRtelevision rx is ok (I have to close and start after changing frequency to receive the stream, but waterfall switch to new frequency immediately; minor problem)
CPU usage is at 30% abt
stream from obs is visible in SDR television
loopback is ok as well (CPU: 45 %)

all my programs + SDRtelevion RX + express transmitter 333kS: CPU 70%
all my programs + SDRtelevion RX + DATVEasy 333kS: CPU 60%
transmit is ok

When I close loopback, activate the pluto and use SDRtelevion for send instead of express transmitter or DATVEasy (press send), CPU jumps to 100% When I stop send, CPU drops to 30% after >5 minutes. This happens with all SR.
So SDRtelevion for TX is not usable for me.

Any ideas? What may be wrong?

Tnx for help
Guenter