Excel 2011 uses 99% of CPU

I have been using Office for Mac 2011 since my switch to Macs; Excel has been OK (a few functions missing) until now.

I use fairly elaborate spreadsheets which I copy and paste into a another worksheet as a linked image for easier printing (excuse the translation, my software is in french) ; this can be done in Excel while pressing shift and clicking on Edit to Paste.

I have never had any problems on my PC with this way of working. All my XLS spreadsheet that have this type of links use over 99% of CPU on my mac (iMac 27, i7 with 8 gig of Ram). I know for sure it is a problem with Excel 2011 because the same file when opened in Excel 2003 in Parallel V6 uses only about 2% CPU!

Has anyone experienced a similar problem? Found a solution beside using Excel in a window environment (which I would like to avoid)?