Will Yosemite Make My Computer Faster or Slower?

You wouldn't see much of a speed difference.

Have a full backup and try Yosemite.

If it doesn't meet your expectation, revert back to Mavericks.

I don't find any problem here.

Best.

It likely won't be any faster than Mavericks. Quite a few users post here with it being very slow and it turns out to be a lot of crapware that is incompatible with Yosemite.

I heard Yosemite is a RAM hog,

That is a misconception propagated by people who do not understand that Apple memory management changed with OS 10.9 Mavericks. For more efficient use of RAM, Mavericks and Yosemite now claim a lot of the free RAM for faster access. This Apple article may help you understand it:

How to use Activity Monitor - Apple Support

The new metrics for evaluating RAM usage are Swaps and Memory Pressure as shown in the little chart at the bottom of the Activity Monitor window when you have the "Memory" tab selected.

Within the last six weeks, I upgraded two of our Macs to Yosemite and see no difference in performance from the prior OS versions installed: 10.9 on a 2012 non-Retina Macbook Pro and 10.8 on a 2011 iMac. Both have the entry-level processors for their respective models, the 2.5Ghz i5.

Neither computer has third-party anti-virus maintenance software, not do that have the questionable software that comes bundled with "name-brand" external hard drives.

One option is to create a new partition (~30- 50 GB), install the new OS, and ‘test drive’ it. If you like/don’t like it it, you can then remove the partition. Do a backup before you do anything. By doing this, if you don’t like it you won’t have to go though the revert process.

Drivers for what?

If you mean the hardware that comes with your Mac, then I wouldn't worry about it. It's not a Dell, and Yosemite is not Windows. It will probably work.

If there's some specific hardware and/or driver issue that you're concerned about then you should probably research it before you install Yosemite.

I have an early 2011 MBP with 8 GB of RAM and it works very well with Yosemite. I did put a SSD in it tho.

Just have a good backup first so if there are issues you can go back to your previous OS.