Impossible to save larger .ods file

I’m not able to save any larger .ods file. For example i have 4 MB calc ODS file (7 sheets each 5 000 lines in 10 rows) – i’m working on it and its ok but if i want to save it then it shows saving in status bar for 10–15 minutes and then freeze. I always have force qiut it and all changes are lost. Any help? Thx

LO version: 4.1 (but same on the previous versions)
System: Mac OS X 10.9.1
Machine: 2,4 GHz Intel Core 2 Duo, 8 GB RAM, 180 GB Kingston SSDnow