Incredibly slow
Under Windows I have used Google products for a long time, but Google's software is terrible and getting worse. Their technical support is nonexistent. As a result I have considered switching to Apple products.
Safari, however, seems nearly unusable on Windows XP in its present state. The biggest problem seems to be the animation in the address bar while pages load; that uses all available processor time, leaving none for Webkit. Consequently the progress indicator prevents the very thing it is meant to indicate. Pages may take several minutes to load if they do not load before the animation starts. I find that setting the priority of the Safari process to 4 (idle) allows Webkit to receive more time and complete sooner.
I have observed Safari using 300M out of 384M RAM. This is the biggest problem in Chrome: it tries to manage several processes (but too few) using hundreds of megabytes of memory each. New tabs are assigned to render processes without regard for the additional load they might impose and cannot be forced into separate processes, so Chrome may attempt to load a URL in a process that is starved of processor time, in need of retrieval from virtual memory, blocking on network traffic, or otherwise unavailable in the near future. Nearly every interface in Chrome uses HTML rendering, which can make it completely unresponsive. Safari seems to be more responsive than Chrome or Firefox, but I need better control of its memory usage.
Other issues: apple.com does not seem to use SSL compatible with Safari. Text input in forms is sometimes inaccurate; Safari occasionally doubles keystrokes or fails to recognize the shift key.
Safari 5.34.57.2-OTHER, Windows XP Pro