Why is the new version so much bigger in file size?
1.7.10 was around 3 MB and 1.8.0 is now 23 MB!?
Are the new icons that big or is there any other reason?
The compressed setup its only slightly bigger. The executable is bigger as it now uses uncompressed icons while the old one had icons compressed that were was uncompressing in memory.
It sounds unnatural, but having a big executable is better from performance point of view - less memory is used.