My late 2012 27” i5, without an SSD got very very slow. Disk Read/Write never gets above 20MB/s with normal computer usage...

I have this issue in my X100 for years now. At first it's just an intermittent problem, camera randomly comes to life despite being switched off and drains the battery. It gets worse over time. Here's my way to cope with it: (1) Leave the switch in the ON position AT ALL TIMES. Don't fiddle with it. (2) Set AUTO POWER OFF – 2 minutes. (3) OVF POWER SAVE MODE – ON This turns off the sensor when used with the optical viewfinder, except when you half press to measure. (4) QUICK START MODE – ON (comes to life in 0.7 instead 2.7 after half pressing the shutter when the camera is sleeping). (5) Be sure to to switch to OVF every time you stop shooting to benefit from OVF Power Save mode. (6) If you are not using the camera for prolonged time, or pack Your gear for transport, remove the battery. # That's it. No problem.