files become too heavy to open, save & close any faster way?

i usually work on multiple page document

but sometimes it becomes it becomes tooo much heavyand took too much time on open, save, close, changing size on 1st page then corel took couple of seconds then again become normal after that i can be able to go on 2nd page and change size etc. there are lots of time when corel took too much time and sometime it crashes and all the work gone.. :(

is there some background process always run or something else which we can stop and make our corel faster?

can i lower the size of corel file and make it lighter or anything else on this ?