Googling provided a couple of pointers, non of which improved matters.
The current Linux IDE doesn't have some of the nice features I like in the windows IDE, so that wasn't an option. I don't do Apple.
After much buggering around , it turns out my anti-virus is the cause of the delays.
I use Avast! Anti-virus, because it's free.
Here's how to fix it.
Click on Active protection.
Now click on Customise by File System Sheild.
Click on Exclusions and Add.
and add in , or browse to the Arduino directory, in my case C:\Program Files (x86)\Arduino\*
now Click OK, and enjoy the rapid compiling we were once used to.