I deleted the tracker database and my N9 behaves like new. No more lag except under heavy stress (more than 9 windows open). I still have all the messages and all my accounts active.

How did you manage that? Do the messages remain after a reboot?

Or did you restore messages after deleting tracker's database?

What, you mean you did "tracker-control -r" as root?
How did you back up your databases? Did you use the tracker-control commands -b/-o or something else?

I don't remember exactly what I did. It was days ago, I just didn't post anything just to make sure it wasn't a placebo effect.

I can see a rm -rf .smartsearch/ as user in the history, but IIRC I dit tracker-processes -r, not sure. Anyway, by deleting smartsearch folder messages and stuff remained intact. The search application still works ok.

DISCLAIMER: This is not going to make your N9 faster, don't go deleting things every day, read my previous posts in this thread to understand what it solved. My N9 had a serious problem in that it started lagging and havind degrading functionality about a day after reboot, and that was probably caused by a corrupt database or corrupt emmc. One symptom was high CPU usage of msgsrvr intermittently.

qwazix,

IMO removing smartsearch folder means the system will just rebuild the index hence the search app will still work...

The way to stop search app from working is to lower smartsearch priority to 10 or to simply delete smartsearch from /usr/bin/

I think tracker-processes just restarts tracker? If so maybe this can be used to kick-start tracker after fixing corruption...Worth investigating further

I got a somewhat similar problem. My N9 homescreens get somehow corrupted, usually after 9 to 10 days of uptime. Application icons start to flicker, change places and eventually I get different kinds of distortion patterns to homescreens (quite similar to the picture you posted). Reboot fixes this.

I wonded what can cause this?

And how to check the longest uptime (without installing any applications) from the terminal? Command uptime just shows the current uptime.

In my case, after several days of uptime, wifi doesn't work as it should. I can't connect to a network or sometimes it does connect but can't browse the web. After a reboot everything goes back to normal.

@OVK, @user/zero
I also experienced this this graphics issue on my N9 once in 2-3 months. Just SSH-ing and killing all meegotouchhome(they are automatically restarted by the watchdog) fixes this for me.
The other two issues that make me reboot my device are:
- updates stop being performed, and there is hanging process pkgmngr. I found recently that can be solved by killing /usr/bin/osa --packages as suggested by TMO user ginngs.
- swap memory runs low, and swappoff/on commands do not free it. Still no solution to this for me.

Once during these 80 days I've had to kill /usr/bin/osa (discussed here).

On day 71 I couldn't no longer open the stock browser, but found the solution of killing /usr/bin/grob here and here.

Yesterday, I was in an area with poor coverage and while trying to make a call I lost cellular communciations completely. Even after returning home, the N9 would not find any cellular network. I tried switching flight mode on and off again several times, also switching the network between 2G, 3G and Dual, to no avail.

Not wanting to break my uptime record, I scanned through the running processes, and found this:
I killed /usr/bin/csd and suddenly the phone registered on the cellular network again!

Carry on till u hit the century