Alf has enjoyed his weekend with installing Windows7 on his home computer...
Unfortunately I need to disagree with Joa: Of course SiDiary is not loading all of your data on the initial start (therefore it doesn't make sense to not sync all data or to put older data into another data folder)!
SiDiary is only accessing the current monthly data file, which means if you start SiDiary these days it will read the file SiDiaryData2009-11.dat from the memory/SDCard. SiDiary's database is fragmented into monthly data files exactly to minimze the processor load in case of a huge database: So having older monthly data files on your mobile gadget won't have any influence to the load performance!
The only thing which would slow down the initial load process would be if the current November file would be really large or that the IO-stream for this file is extremely slow (i.e. because of a damaged data file, SDCard problem or something like that).
You could try the following: Move all data files from the current data folder on your mobile device into another location and see if the start performance has changed. Then copy back the current monthly data file and check again the starting sequence. Then copy back all data files. (step 2 and 3 should not show recognizable differences for starting the app).
You could also try locating the data folder into the phones memory vs. a SDCard location.