I disagree that perceptible slowdowns don’t happen on Mac with SSD. On my MacBook Pro Retina with 16 GB RAM and a 500 GB SSD (over 200 GB free), I can easily create scenario in which pageouts start, soon to be followed by the dreaded spinning ball. If, for example, I keep open my normal suite of DEVONthink Pro Office databases and other apps, then start doing photo editing with Aperture and Intensify Pro, I can quickly use all available free RAM.
Indeed, just with my normal suite of apps and databases (leaving over 8 GB free RAM after a restart), available free RAM declines over time to the point that pageouts start, unless I take preventative action. That may take several days or several weeks of computer use, depending on what I’ve been doing. Why? Apple’s memory management approaches, which try to keep frequently used data available as inactive RAM space but free up inactive data when no longer needed, isn’t perfect. Over time, the result is that free physical RAM declines. At some point, Virtual Memory swap files become active, with data being frequently swapped back and forth between RAM and disk swap files in order to allow procedures to go to completion. Yes, even with an SSD that can slow down the computer very appreciably.
For example, I subscribe to several journals and use Safari to peruse them each week. In going through the table of contents I’ll quickly open articles of possible interest in new tabs for further inspection as to their value for download to a database. After skimming each article I’ll either delete it as not sufficiently interesting, or capture it to a database and then delete the tab. Over time, Safari becomes a major memory hog when used this way, as it doesn’t free up all inactive memory. Quitting and relaunching Safari can release gigabytes of free RAM! Likewise, when I’ve been hammering away working my DEVONthink Pro Office databases, DEVONthink requires more and more memory space, some of which can be recovered by a quit and relaunch. At some point, to maintain an acceptable headroom of free RAM I’ll decide that the best approach is a computer restart.
I also disagree that preventive maintenance of OS X is merely an unnecessary placebo.
Every few weeks I run Apple’s Disk Utility routines to repair permissions and to check the disk. I just ran it and it repaired two minor permissions issues and found that the disk was OK. But since I bought this MacBook Pro it has found and repaired disk errors on 4 occasions. If I had never checked, I suspect disk directory errors could have accumulated to the point of data loss! I’ve never had a hard drive crash (except on my old TiBook when it was dropped). I want to avoid such a problem, and checking for possible disk errors gives early warning of problems and can avoid serious problems.
I use C0cktail every few weeks to clear caches, etc. as preventive maintenance. I’ve never had to do a reinstall of OS X (except on one occasion when I checked a user problem by downloading a hack utility that destroyed my operating system, too). Most of the maintenance routines run by C0cktail are routines that are built into the Terminal app, but more user-friendly in C0cktail’s environment. Cache files, as the name implies, are a shortcut support to frequently called actions. They can save time. But if a bit gets twiddled in a cache file, strange things can happen. My attitude is that any time my computer does something that seems flaky, I’m going to run preventative maintenance on the operating system. CAUTION: Never use a maintenance utility that hasn’t been upgraded to the currently installed version of OS X!
I try to keep OS X basically stock. I avoid installing hack utilities that change the appearance or functions of OS X, on the grounds that, if not well designed and tested they can cause errors, and almost certainly will do so after the next update of OS X if not properly updated. Perhaps I lose the conveniences promised by such utilities; but as payback I avoid a lot of grief when they go wonky.
Some people pride themselves on how long their computer has been running without a restart. I don’t think that’s a good approach to keeping the computer reliable. Put it this way: I wouldn’t be able to afford a current Mac if it were designed to be totally error-tolerant. Memory errors can and do happen, and if they accumulate enough will cause problems, including possible data damage or loss. A restart guarantees a fresh load of the operating system to memory. I do that at least every few weeks.
Perhaps I’m a bit of a fanatic about keeping my Macs clean and efficient, but my approaches take little time. I ascribe the fact that I don’t encounter database errors and don’t lose data to those actions, and I don’t see spinning balls. I’m also a bit fanatical about keeping backups, even though I haven’t had to resort to one for years. I use Time Machine because it is so convenient and is automatic when I’m using my MacBook Pro on my desk. I also store backups on a portable drive offsite, in a safety deposit box at my bank, in case of loss of all my computer equipment at home by burglary, fire or whatever.