I haven't experienced any issues with Safari causing memory problems, although I'm betting that I restart it every few days (you know, always changing something). I've had it running for 3 or 4 days at a time without being touched and no issue.
As to power consumption, it's interesting. The "low point" for the house is about 1.2 kWh, it just doesn't go below that under any circumstances short of a power failure. I tracked all of that down and can account for it (DirecTV receivers, a couple of MacMinis, a few switches, phone systems, HAI alarm, security DVR, refrigerators and cameras, etc. But even that isn't bad. Average consumption (without AC) is about 2kW or 40-50 kWh per day, mostly because I run a lot of exterior lighting at night for security. I'm quite pleased with all of that, except ...
Summer is another matter. AC here in the desert (where it can reach 120 with lows in the 90s) is the big killer. By managing the thermostats with the HAI system I can control some of that. At night only the Master Bedroom runs (kids are all moved out), remainder of the house is setup to 80 degrees. Programming on the HAI allows me to "zone out" the Den, upstairs and exercise room (I really need to use that room more) when they're not being used. The AC unit in the workshop is only used when I'm actually in there working on a car or something, not to often but handy when detailing. Power draw when all of the AC compressors are running, or 5 of the 6 anyway, can peak real fast. Today we reached about 95 degrees, the house was empty (so everything was set back by the HAI programming, or "away" mode), so when I returned home and disarmed the temps were reset. It peaked at 24.1kWh for a while wile the compressors were running, then settles down.
After a few months of experimenting, ALL of the thermostat settings are automatic, we hardly ever touch them, HAI system does it all. If we leave a patio door open, that area is turned off, back on when the door is secured. You get the idea. It's all logical and it REALLY makes a huge difference.
The house is about 14 years old, the sun exposure is perfect (south side is the garage which buffers the house) and it is extremely well insulated (6" exterior walls). One thing I did notice which is important is that I replaced one of the 4.5 Ton AC compressors last year, the old one draws about 5 kWh when running, the new one only draws 3.5 kWh. Something to be said for high efficiency appliances.
Power monitoring has always been part of my hobby, I've had numerous systems, latest for the past two years is a Brultech monitor with seven channels active (main house, AC units, oven) connected to their Dashbox appliance. It's probably a $1k investment but I KNOW it has a short 1 or 2 year payback in energy savings by being able to know exactly where the power is being used (and it's kinda cool).