Yosemite slowing down macbook air performance

Question

Ever since upgrading to yosemite, my 2011 macbook air 11' has been very noticeably sluggish compared to how it was with mavericks. At first i thought it might be from some conflicts from the previous OS, so I did a completely fresh install with yosemite, but it's still dragging and sluggish, especially with any kind of graphics intensive process. I know the air isn't supposed to be a marvel at graphics performance, but I never had these performance issues with mavericks.
Is yosemite just too resource heavy for my macbook air? I wonder if I'd just be better off going back to mavericks. However, if there's some kind of settings I need to adjust, I'd be happy to experiment. I've already tried the 'reduce transparency' trick, but it didn't do much (not that I noticed anyways).

Answer 1

Gatekeeper is described here: OS X: About Gatekeeper  - Apple Support. It is only one defense to protect you from inadvertently installing malware, and an effective defense does not rely upon only one method.
... I can use software that isn't officially "identified" by apple, even though it is trusted.
Apple's philosophy is such that a Mac user with Admin privileges always has control over what he or she installs. As I wrote Gatekeeper will serve to protect you against inadvertently installing malware, including the adware that is affecting your Mac. Adware does not get installed on its own - it requires your explicit permission, which you provided by supplying your Admin name and password. When that dialog appears, it should be expected, not a surprise, and its implications should be clearly understood. By providing your credentials OS X concludes you know what you're doing and the reason you're doing it. Determining the "trusted" aspect of software thereby falls to you.
In your case, by choosing the "anywhere" option you effectively circumvented this basic OS X security feature.
The problem with adware is that it relies upon deception to convince you that it's legitimate software offered for some beneficial purpose, when in fact all it will do is interfere with your normal activity and possibly crash your Mac.
Is there anything I can do to possibly identify which apps may be slowing my system down?
Yes, although you installed quite a number of them. For troubleshooting, read below the line that follows the end of this post.
An EtreCheck report generated on a Mac as it ships from Apple will show no entries under Kernel Extensions, Launch Agents, User Launch Agents, Safari Extensions, 3rd Party Preference Panes, etc. Everything that appears under those headings is there because you installed them. As I wrote it's a user's responsibility to understand the specific benefits they are intended to convey, the effects they will have, and the means of uninstalling them should they result in unacceptable performance - which was your original complaint.
It's also possible that the slowdowns are not caused by software, but given the extent to which your system has been modified, hardware failure is less likely than incompatible or poorly implemented software.
... anything that isn't officially "identified" by apple is adware?
Although OS X incorporates specific prohibitions against installing common malware, they can hardly attempt to classify specific user-installed modifications as adware. The only certain way to do that would be to prevent user-installed system modifications altogether, in the same manner as they do with iOS (iPads and iPhones).
Adware's appearance changes approximately every day. Their pathetic developers are desperate to change its appearance in an effort to continue their deceptive tactics, and a simple change of a file name precludes a reliable automated means of intercepting it. That's the reason it's incumbent upon Mac users to educate themselves about its appearance so that they are not so easily gulled into installing some junk. Gatekeeper merely helps you understand that's what you'd be doing.
Back up your Mac if  you have not already done so. To learn how to to that read Mac Basics: Time Machine backs up your Mac - Apple Support.
If your Mac is momentarily unresponsive, consider the following.
Launch the Console app - it is in your Utilities folder. You can find it by selecting Utilities from the Finder's Go menu.
If the log list column on the left is not already displayed, show the log list by selecting Show Log List from Console's View menu. Select Show Toolbar if it is not already shown.
Locate system.log in the list and select it. Many date and time-stamped entries will appear, hundreds of them, and you must find the entries relevant to your Mac's problem.
To do that click the Clear Display button in the Toolbar. All previously displayed log entries will be disappear.
Next: Perform whatever actions cause the Mac to exhibit the slow behavior. If the problem is caused by errors logged by the system, the Console window will show them being recorded in system.log.
One or more of them, along with their time stamps, may reveal the reason for the problem you describe.
Copy and paste those log entries in a reply. If hundreds of the same repetitive messages appear, please edit them before posting. There should be no need for more than a few log entries.
Most of the entries will be cryptic but will contain information you might consider personal such as your Mac's name. If you do not want that information to appear, delete or obscure it when posting your reply. Leave enough information so that the entries can be deciphered.