Buy a fast SSD, but disable atime.

A Solid State Drive is a disk without moving parts. It has no heads to move nor platters to rotate when seeking. This makes access times on these disks a lot lower. Also the throughput is optimized by accessing many storage chips in parallel. Xubuntu is by default using an “ext4” filesystem which is journaled. One of the features of this file system is that it keeps track of the “last access time” or “atime” in short. This is nice, but it means that every read causes a write as well. Since you in general don’t need this “last access time” you can safely disable it by adding the “noatime” flag (nodiratime is implied) to the partition options of your ext4 partitions in the “/etc/fstab” file (see lifehacker). One of the drawbacks I found is that “Mutt” is not working correctly. But note that whenever you make a backup of your valuable files you will probably also update the atime and confuse Mutt (or any other program that relies on atime).