Anna, do you mean the Finds are not appearing in your browser?
Also, what is the version number on your browser?
Regarding Mavericks, it is hard to judge what makes something worth the effort because everyone has different requirements. But generally the latest versions are going to get more love an attention than older ones, so often you're better off in areas like security. Later this year Apple will release Yosemite, and my experience is that it is better to move with Apple than to make big step changes in OS (e.g. from Lion to Yosemite).
On the other hand, switching to Chrome might be less disruptive than switching to another OS.
If anyone is having this problem and knows how to use the console in the browser, please take a look and check whether any error messages are appearing there. To do so, first enable Developer mode by checking "Show Develop Menu in Menu Bar" in the Advanced section of the Preferences.
Then select "Show Error Console" in the develop menu and load a page on YLF where you see the problem. There will be a bunch of messages saying "Invalid CSS property declaration at: *", which can be ignored. But are there any other messages?