How can I safely purge my slow Safari?

Question

My edition of Safari, running under Mavericks 10.9.5, has been getting noticeably slow this last month or so, especially in resolving websites to screen. In fact, sometimes Safari will fail to acquire even a reliable site and will instead stall. I thought this was possibly a DNS problem on my setup but, having thoroughly checked out my router settings and network settings in the machines that I run, this is definitely not the case. Indeed, accessing the self same websites on a separate Windows machine has revealed no problems. So clearly Safari (v.7.1.2) is, for whatever reason, running slowly. I don't think I'm alone in this. I might add that I run no browser extensions and generally try to keep a clean machine, so this is very unlikely to be caused by any third-party software.
Possibly, on my Mac some cached areas of Safari are overflowing and are now causing this slowdown. Word has it that, unlike many other browsers, Safari doesn't manage the cached areas too well and so can eventually get slow. So, how can I deal with them without losing, for example, all my Privacy settings (websites that are allowed to set cookies), all my Reading List of regularly-visited sites, and for that matter my personalised layout of Safari? I see that there are several functions within Safari for doing purging, but I've no idea as to precisely what each one does.
For instance, what does Reset Safari do? (Safari/Reset Safari). Presumably, if I used it, I'd lose all my Safari settings?
In the Develop menu, there's Empty Caches. But which particular caches would this clear? And again, would I lose all personal settings?
And how about History/Clear History? Seems a good chance I'd lose all websites on my Reading List.
I've seen it suggested in another forum thread that the folder Library/Preferences/System Configuration should be deleted and allowed to re-form with a Restart, but looking at the normal contents of that folder it doesn't particularly strike me that re-forming it would be of any help in this context.
I've reported the slowness to Apple via their Feedback webpage, just in case the problem lies instead at a software design level. But of course you get no response from Feedback. Certainly, the latest Safari update, 7.1.2, downloaded a couple of days ago, has made no difference to this.

Answer 1

Please answer as many of the following questions as you can. You may already have answered some of them. In that case, there's no need to repeat the answers.
Back up all data before making any changes.
Have you restarted your router and your broadband device (if they're separate) since you first noticed the problem? If not, do that now and see whether there's any change.
If your browser is Safari, then from the Safari menu bar, select
          Safari ▹ Preferences... ▹ Privacy ▹ Remove All Website Data
and confirm. If the Downloads button (with the icon of a downward-pointing arrow) is showing in the toolbar, click it and then click Clear in the box that appears. The download history will be removed. Any change?
If you're running OS X 10.9 or later, select the Advanced tab in the Preferences window and uncheck the box marked
          Stop plug-ins to save power
Any change?
Quit and relaunch the browser. Any change?
Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.
Are any other web browsers installed, and are they the same? What about other Internet applications, such as iTunes and the App Store?
If other browsers and Internet applications are also affected, follow these instructions and test. Any change?
If Parental Controls is active for any user, please turn it off and test. Any change?
If only Safari is affected, launch the Activity Monitor application and enter "web" (without the quotes) in the search box. If a process named "Safari Web Content" is shown in red or is using more than about 5% of a CPU, select it and force it to quit by clicking the X or Quit Process button in the toolbar of the window. There may be more than one such process. Any improvement?
Follow the instructions in this support article. Any change?
Open the iCloud preference pane and uncheck the box marked Photos, if it's checked. Any change?
Are there any other devices on the same network that can browse the Web, and are they affected?
If you can test Safari on another network, is it the same there?
If you connect to your router with Wi-Fi and you can also connect with Ethernet, do that and turn off Wi-Fi. Any difference?