Yosemite slow on MacBook Pro mid 2012

Question

Hi Anyone
My MacBook Pro, 13 inch mid 2010, 2.5GHz intel Core i5, 4GB 1600 MHz, Intel HD Graphics 4000 1024 MB
Updated to os x Yosemite 10.10 (German Version)
Problems:-
Slow in loading Apps, e.g. Safari load very slow and if I want to type something on search the waiting-wheel keep turning, after a long while it does find everything I want but then when I click on the menu list the waiting start all over again, so is that with other Apps.
The next problem is that it is using up memory fast, and I have to use the Memory Clean all the time beside waiting!
I have notice by the Systeminfo, System report Hardware/Harddisk/Logic Volum Group:
Name: Macintosch HD
Size:  499.25 GB
Free: 19 MB !!!! (is this the problem)
or do I have to upgrade to 8 GB!
Thanks

Answer 1

It's normal since Mavericks for almost all memory to be in use, either by applications or by the file cache. That's what you should want, since unused memory is going to waste. The relevant measure of whether memory is in short supply is what Apple calls "memory pressure."
Apple's explanation of memory pressure is here. If you want a more detailed, technical description, see here.
Get rid of "Memory Clean," which is worse than useless.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Console in the icon grid.
The title of the Console window should be All Messages. If it isn't, select
          SYSTEM LOG QUERIES ▹ All Messages
from the log list on the left. If you don't see that list, select
          View ▹ Show Log List
from the menu bar at the top of the screen. Click the Clear Display icon in the toolbar. Then take one of the actions that you're having trouble with. Select any messages that appear in the Console window. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.
The log contains a vast amount of information, almost all of which is irrelevant to solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.
Please don't indiscriminately dump thousands of lines from the log into this discussion.
Please don't post screenshots of log messages—post the text.
Some private information, such as your name, may appear in the log. Anonymize before posting.