try a frameskip of 1 to see if that changes something (ctrl-f8)

Thanks for your fast answer. But i am sorry. frameskip does not solve the problem.

While dosbox run the cpu perfomance is:
about 20% (if no "lag")
then (every 10 seconds) it jumps to 100% for about 2 seconds.

But not every cpu (dual-core) goes up to 100%! While one goes to 100% the other cpu goes down (about 0-10%)...

I wonder why it is exactly an interval of 10 seconds....

I found another interessting thing. If i use the notebook with external power supply the lag-intervall is about 30 seconds. if akku is use 10 seconds....

sounds like your cpu scheduling might be interfering.
have you tried disabling it, to see if it influences something ?

cpufreq-selector -g performance

No i tried the cpufreq-selector -g performance (and powersave). No difference.

I think the cpu jump to 100% perhaps is only an result of the lags, not the cause. But i dont know...
And somtetimes the cpu only jumps to about 70%. But the system lags, too.

Just a shot in the dark but try to disable everything in the config file that can be disabled, like sound, joystick etc.
Have you tried a different output method? (output=...)

Ok. I will try some different options... This will take a few hours 😉

Have you checked the Process tab in the program in that screenshot to see which specific program/process is taking up 100% of the CPU during those usage spikes?

What is that program, anyway? Looks nifty. (I can't stand thwacking through various arguments for "ps" on the command line trying to find out what's going on.)

That's the Gnome Task Manager equivalent. On a Athlon XP 2200 it takes ~80% CPU when displaying this tab 😉

Actually i could not reproduce the posted issue. I figgured out that something was wrong with my cpu(-controlling). One of the cpu ran at 1500Mhz the other at 2100. (2100 is right).
After restarting the System i have no further problems.

I will keep an eye on this...

Thanks for all your help.

Glad you got it sorted, at least for now.