There's a simple answer to that question. As I mentioned in the first post in this series, "It's my machine dagnabbit". The simple answer is that applets consume resources that can be better used by by the customer.
At an absolute minimum, each applet process consumes a process (no duh - that was a stupid statement, Larry). But you need to realize that each process on Windows consumes a significant amount of system resources - you can see this in Vista's taskmgr.
There are three columns that are interesting: Working Set, Commit Size and Memory. Commit Size is the amount of memory reserved for the process (so can be insanely large , Working Set is the amount of physical memory that the process is currently consuming, and Memory is the amount of working set that's not being used by DLLs.
On my machine, to pick on two applets that I have running, you find:
- FlashUtil9d.exe consuming 4.5M of working set, 1.3M of commitment and 760K of Memory
- FwcMgmt.exe (the ISA firewall client) consuming 4M of working set, 1.6M of commitment and 300K of Memory
That 700K is real, physical RAM that's being actively used by the process (otherwise it would have been swapped out). With multiple applets running, it adds up FAST. On todays big machines, this isn't a big deal, but on a machine with less memory, it can be crippling.
In my last post, I categorized applets into 4 categories (updaters, tray notification handlers, helper applications and services). In addition to the common issues mentioned above, each of these has its own special set of issues associated with it.
Updaters often to run all the time, even though they're only actually doing work once a day (or once a month). That means that they consume resources all the time that they're active. Adding insult to injury, on my machine at home, I have an updater that is manifested to require elevation (which means I get the "your app requires elevation" popup whenever it tries to run).
Tray notification handlers also run all the time, and adding insult to injury, they clutter up the notification area. The more items in the notification area, the less useful it is. This is actually the primary justification for the "big 4" notification area items in Vista - people kept on finding that the 3rd party notification area icons crowded out functionality they wanted to access. In addition, notification handlers seem to love popping up toast on the desktop, which often interrupts the user. In addition, since tray handlers often run synchronously at startup, they delay system boot time.
Helper applications don't have any specific issues, from what I've seen. They just consume resources when they're running.
Services are both good and bad. Each Windows service has a start type which lets the system know what to do with the service on startup. There are 3 relevant start types for most services: AutoStart, DemandStart and Disabled. When a service is marked as AutoStart, it starts on every boot of the system, which degrades the system startup time. In addition, because services often run in highly privileged accounts, the author of the service needs to take a great deal of care to ensure that they don't introduce security holes into the system. Before Vista, high privileged services were notorious for popping up UI on the user's desktop, a practice so dangerous, it justified its own category of security threat ("shatter attacks"). In Vista, changes were made to eliminate classic shatter attacks for all subsequent versions of the OS, so fortunately this issue isn't as grave as it was in the past.
Tomorrow: So how do you mitigate the damage that applets can cause?