Well, you could go to Tools - Options - Privacy - and in the Cookies - Accept Cookies From Sites in the drop down menu there should be three options... 1) They expire, 2) I close FireFox, and 3) Ask me every time. I use number two so that all my cookies are cleared every time Firefox closes.
Edit: I don't see why Spy Sweeper should take that long to scan your system either (of course it depends on a lot of things) on my Laptop: 1GhZ Celeron, 256 RAM, 10Gig HDD, it takes about 15 minutes and on the computer in my signature it takes about 30 minutes.
Dell Inspiron 9400 Notebook 120GB 5400RPM SATA HDD, 500GB 7200RPM SATA External HDD, DVD+-RW, DVD+-RW External, Mobile Intel Calistoga i945PM, Intel Core 2 Duo 2.0 GhZ, 2GB DDR2-667MhZ Dual Channel SDRAM, Nvidia GeForce GO 7900 GS 256MB Single-Pipe.
TinyXP Rev05, PerfectDisk, TuneUp Utilities, Window Washer, Nod32, Bo-Clean, SuperAntiSpyware Pro, Spyware Blaster, Comodo Firewall Pro.