Any zip type programme will condense files and thus save you transmission times if then attached to an email or sent direct.
I have used ZipCentral for 2 years and it is one of the best freeware products.
Initially in Options/configuration set the default Add folder to wherever you want your created zip files to go (so you can find them).
Close it down.
In Explorer if you right click on the file you want compressed, click on Add to "filename".zip in the Context options offered.
This will re-start ZipCentral.
Set your compression level - I use maximum (slowest) and click OK.
It will then compress the file and show you its compressed file size. You can see if it has compressed with no errors by clicking on Test.
Compressed file will now be in the folder you originally specified - ready to send.