"time for screen refresh and monitor sync" is how long in milliseconds that the cpu has to draw a single frame. After that frame is drawn then shown, the refresh will "refresh" or restart the drawing process again. This is also in conjunction with syncronizing these "frames" to the refresh rate of your moniter, 60 mhz, 80 mhz etc. Im sure theres a better explanation from the more knowledgable members of the forum.

First, try to stick to the "under 10" rule for any statistic in the debug panel. If the number reaches 10, then the drop in FPS becomes more noticable. You also have to weigh the worth of what is running and if its really worth it. Say for example the execution time for entity actions is 2.3ms in the debug panel. But say the only things that are running is the player action, and say 600 grass sprites using the "vec_dist" function every frame. If only the player and 600 actions are causing the 2.3 ms delay, youre going to have to cut down on the amount of grass sprites running the script, or produce a more efficient way of coding the sprites. This also applies to every other variable in the panel like the refresh time. (use smaller textures,lower polycounts, use PCX or DDS coming soon)

In reguards to the refresh being 45,

1. do you have alot of sprites or models with transparency (espesially tga images) on screen at once? Especially close to the camera?
2. Do you have alot of hi-poly models being visible at once?
3. Are you using Mip-Maps for your terrain?
4. Are the sizes of your textures for both models and blocks in the power of 2?
5. How many panels are visible, and what image format are they?
6. Are you running in window mode?(I think window mode produces a slower refresh rate than fullscreen)

There are ALOT of different factors that can increment the refresh rate, but we dont have enough to work with. Run your level and move the camera to the place(s) where you get the ref 45 in the stats panel. Tell us exactly what you see and we can help you more.