your cpu maybe can't handle more cycles ?

Version of DOSBox?
What CPU do you have?
An example of game that runs slow?

Try typing core dynamic at the DOSBox Z:\> prompt before running a game.

hmm using intel pentium 3 450. its an old one i know but for old games i use it

for dosbox that is a bit slow.
you could take a look here
http://dosbox.sourceforge.net/oldwiki/index.p … eDemandingGames

thx but games like space quest and police quest lands of lore running fine .

but for wing commander 2 i need ctrl-12 but when i use that the whole dosbox running slow

how i can get run wc2 smoothly?

It's easy: open DOSBox in windowed mode, and task manager. Now start a "demanding" game (in your case, that would be nearly any game, more on that later), and look at the CPU utilization. Adjust the cycles until CPU util is _below_ 100% (maybe hitting 100% in "spikes"). Now you have an idea about how many cycles your system can take. If you set cycles larger than the "100% threshold", DOSBox will get slower and slower, until your system begins to "choke". You may be able to get a few percent better performance by using a CVS build (Gulizoka's or ykhwong's), choosing a different output method (Direct3D, OpenGL), or increasing frameskip.

OK, you probably don't want to hear this, but it's a fact: your system is _way_ too slow for DOSBox. It might be strong enough to handle "simple" 2D games, like the ones you gave as examples, but with anything 3D, you'll not be able to get good framerates. You have to understand how 3D works without hardware 3D acceleration: the CPU has to calculate every single pixel on the screen, without the help of special hardware.