my macbook air 2012 now takes too much booting time approx 10-15 min and its too much laggy that i have to wait 5 min for opening an app. it was working fine but when i reinstalled mac os bpressing command+R this problem appeared.

Yes, Please post the EtreCheck output

<https://discussions.apple.com/docs/DOC-6174> or <https://etrecheck.com>

Use the EtreCheck "Share" button to "Copy Report" (See the image below)

And then Paste in a "Reply" to this thread.

If, AND ONLY IF, you get the error:

"The message contains invalid characters"

then try posting to PasteBin.com, and give us a PasteBin URL link.

<http://pastebin.com/>

.

EtreCheck is a tool that helps Apple Support Community volunteers debug problems without any access to the troubled computers. Debugging problems can be a difficult task even when the machine is in front of you. Attempting it via a discussion forum is extremely difficult. EtreCheck is a great help that regards.

2)

Also make sure your boot device is highlighted in System Preferences -> Startup Disk

You may need to click on the Padlock in the lower left corner and unlock the Startup Disk preferences before you will see if your boot disk is highlighted.

If your boot disk is NOT highlighted, it can slow down your boot. NOT 10-15 minutes, but that could be contributing to the slow boot time.

3)

You should also try an SMC reset and an NVRAM reset

<Reset the System Management Controller (SMC) on your Mac - Apple Support>

<How to reset NVRAM on your Mac - Apple Support>

4)

Try booting into Safe mode

<http://support.apple.com/kb/ht1564>

This will not load any 3rd party additions, it will load some more conservative Apple drivers (may cause screen flicker), and it will clear some kernel caches (a cache is saved data in a form that can speed up a program, but is totally redundant to the original source, and thus can be safely cleared). Booting into Safe mode is just an experiment, but can often times eliminate any 3rd party interference, or a cached item out-of-sync with the world.

Booting into Safe mode is generally slower, but if it happens faster, that would be a strong indication you have 3rd party additions that are slowing down your boot.

Also booting into Safe mode clears some kernel caches, and while the next boot will be slightly slower while the kernel rebuilds it cache, all boots after that should be better, assuming there is an issue with the kernel cache.

did the shopkeeper do anything resembling diagnosis or just drop his pants and make words come out of his rear end?

please post an etrecheck report for analysis of your system

www.etrecheck.com