I have updated my L925 to w8.1.

So far so good.
Guess I have live without the Me FB integration mode anymore. I have to open FB everytime to check new notifications.

But i liked the new FB Messenger app. Really handy at times.

others, felt like it's not much improvement.

My 925 is getting sluggish, and having problem opening whatsapp.

have updating all the necessary apps to latest version, yet it is still slow.

Now my disk space is 700MB. Could this be the cause of the sluggishness?

I've had 925 for over 2 years now. Now this problem came (although some sluggishness do occur but not that bad compared to current problem).

Any idea why and how to fix this?

format? you mean do a rest back to factory default?

actually what happens if i do that?
will all my contacts be gone, and all my whatsapp chats be wiped out, photos and stuff will be gone forever?

Ok so i've done the phone hard reset / formatting 2 days ago.

Did a thorough backup of all photos, videos , docs to my PC prior to formatting.

Then after format, it asked me whether I want to transfer all my previous backup into my formatted 925, or start over with a new,fresh, clean phone?

I chose the latter, and boy, now my 925 runs smooth as butter. No problem with whatsapp now, or any sluggishness.

Guess I could prolong my 925 to another, say, 5 more years?