A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I had this problem and looked all over to find a solution with no luck trying various online suggestions. My copy of Excel 2013 would open right away in the safe mode but take about 30 seconds to open when started normally. The problem turned out to be a corrupted file in the hidden directory c:\users"your name"\AppData\Roaming\Microsoft\Excel.
It seems that this is where Excel places backups of files being worked on and if these files become corrupt it delays the startup of Excel. Deleting all the files in this directory (leaving the sub-directory XLSTART alone) completely fixed the problem. I had tried uninstalling and re-installing office with no luck. Apparently uninstalling office does not delete files in this directory.