Is there any way I can make it import one page per minute or something like that?
Unfortunately, not without changes to the coding, there is not option for that.
In the next release for Facebook Events we are working on improving the efficiency of the script, but there is only so much we can do as it will still rely on Facebook for the results and the speed at which a server can process those results.
What are you currently setting the automatic import frequency to? Do you think you could manually import all the unimported events and then set that to hourly it would be able to keep up with the load?