you dont think that SSD increases processing, but you do think that RAM does? ???
Harddisks are easily the biggest bottleneck on computers, so an SSD will be by far the best way to improve performance for most people. adding RAM only helps if you are maxing out the amount the system has, using...
seems the first place to start is to remove/reinstall Outlook. if problems occured after upgrading the OS, then rolling back seems the second thing to do. spending money on faster hardware to dodge troubleshoooting is probably the last thing to do. Going with an SSD will mean a reinstall...
i dont know much about Mac's but i know this: computer hardware does not get slower over time (bar recoverable harddisk failures), and adding RAM does not speed up a computer. this is a software issue. in Windows land the typical solution is to defrag and uninstall all the crufty shite you've...