i dont know about you but with normal kernel configuration i have better responding device

just changed maximum clock via maxcpu- or do you mean stock kernel?

reflash to a clean system, install swapplube, install the cssu, and install theme customizer go to control panel go to theme customizer and select fast transitions and you should have a fast phone, i used to have the same problems as you, i think probably because i installed something the power kernel didnt like, or the overclocking had a negative impact, so far am with stock kernel and ive been running fine

Is it just me, or does anyone else see a pattern here?

The biggest single reason I've seen on this forum for people having a crappy phone: They install crap without understanding what it is, what it does, or how it works. For the love of all things holy, if you don't understand what something is, or how it works, don't install it until you do! That includes "speed patches", applications, drivers, kernels, and even the beloved CSSU. If you can't read a wiki / thread for something and understand how it works, how to configure it, and what it's designed to do, you get what you deserve if you install it. Doubly so if it's from extras-devel or a random zip/deb file. Would you take a drug from a random person because they say it will make you feel better or run faster, with no indication of what it is, how it works, or if it's safe? Why would you do that to your N900?

I can tell you I've not missed a single call since PR 1.0, which had some problems with that without any mods at all. Since PR 1.1 it's been rock solid at answering calls. I can also tell you I have a crap-ton of stuff installed, including K49, h.e.n., CSSU, boat loads of apps, and with mild exceptions very few things have caused issues. (And most of those are things I hesitated installing, and didn't follow my own advice on. )

Some of the key things I advise people to do to "fix" problems like what you're having above (besides not installing crap) are as follows:

Orientation swap (portrait mode) - Solution: Just don't. Nothing was designed to run in portrait mode, not one blessed thing. It only works because of hacks and patches. Transitioning between the two can take forever, even with the cute "flip" animation turned off. I run CSSU locked in landscape mode, and it's just rock solid. This device was made and sold as a landscape device. If you wanted a portrait phone you made a poor purchasing decision, which the slide out keyboard should have clued you into pre-purchase.

Conversations Inbox Widget - Can occasionally cause the desktop to lock, crash, or run at 100%. It seems to always happen when an SMS is received, but causes the message to not show an indicator/beep. On killing hildon-desktop, or rebooting, the message comes through as it restarts, before widget show up. When I was running it, I found it's propensity to cause a lockup grew with the size of the database. (The same db file also houses e-mail, SMS, call logs, etc.) If you want to keep old messages, do so with glogarchive or via the OVI/PC suite. Since disabling this widget I've had 0 desktop freezes. Solution: Disable the widget, or at least clean up/remove old SMS & compact the database on occasion.

Swapspace fragmentation - Over time the N900 slows because the swap space becomes somewhat fragmented. This is a kernel issue and is common on pretty much all linux systems. It presents itself faster on the N900 because of the amount of swapping done in heavy usage. Solution: Every couple days turn off the main swap space, then turn it back on. If you have lots loaded (esp CSSU) you may need to setup a small swap space in a loopback device, or on the SD card and enable it for the excess to "spill" into when you turn swap off. That clears out all the old clutter and swaps back out only stuff it needs too. Or, just reboot on occasion.

And if you've already installed a crap-patch, without knowing what it's done, don't assume an uninstall will fix it. Lots of the patches change kernel values and tweak settings files when they run, which they don't undo when uninstalled. If you have a crappy system because you once installed crap, the simplest way to fix it is to do a backup, re-flash, and recover said backup. (Packages/contacts only!) The harder way is to figure out exactly what was done and undo it... but if you knew how to do that, you probably wouldn't have installed such a thing to start with.

And in case there's any doubt that an N900 can run stably for a long time, I submit this Conky screen shot, just taken a bit ago with my N900. Note the uptime.

GOT IT! (well for me^^)

first i reflashed and set up my phone from the beginning (only restore of contacts/communication, nothing else). i installed my usual stuff (i.e. cssu (testing), kp v49, maxcpu- but not speedpatch or anything "patchy").
it lagged again, so i thought about kp v49 being the cause and bricked my device (don't say anything )

then i started like i did above again with a complete clean device and there was this lag again when unlocking the phone (i.e. 5secs to start phone from desktop).
things i did install this time:
- cssu (testing)
- kp v42 (from extras repo)
- maxcpu
- conky
again that lag.

uninstalled kp and maxcpu, reboot - no lag.

then i installed kp v49, reboot - no lag.

maxcpu installed: there you go again - lag! (of course rebooted) and completely without even touching the widget!

uninstallation and reboot: no lag at all.

so for me, maxcpu caused the lags.

btw: is there any other solution to overclock the device in an user-friendly way (=via gui)?

for god sake leave the hell of speed patch it has nothing to do with your call delay problem
it only improves ui response mostly with multitasking
but battery patch improves the call receive
read the change log :
http://maemo.org/packages/view/batterypatch-testing/
but it was applied about weak ago

in short :

things can cause lags within receiving calls are :

1- settings recaller app to auto record when N900 rings
2- having a lot a lot of widgets on the desktop
3- having messed up N900 especially in path /home/user/

end

not sure about maxcpu .. i don't have it nor i don't think it has anything to do with lags

first i couldn't imagine myself, but the lag is reproducable with maxcpu, so at least for my config (the device is nearly clean- same goes for the desktop) it is definitively the cause.

try Qcpufreq

Nice detective work. You did exactly the right things to find out what was going on. Some things are harder to figure out, this one you lucked out on, that it wasn't settings something in the system that was slowing it down, installed or not. Best is to install things one at a time until you get to the thing that killed you, then don't re-install it again after a clean wipe!

I can tell you than any screen widget has the potential to cause lag. Any time a widget registers, it gets requests from the desktop manager on occasion. Anything from being scrolled onto screen, periodic updates, events, etc. They also have the ability to register all kinds of hooks into the desktop and the system, and generally are the main reason for display lag. If you can terminal in via ssh and it's all running fine, but your display is laggy: It's likely a widget.

Tons. I use QBW (QueenBeeWidget) for about 10 things on my various desktops. There are scripts out there for just about everything. You can set it up to just add a button that runs the kernel-config command to load a profile on press. And if you want something custom, you can make your own pretty easily.

Mind you, you can cause lag with QBW too if you're not careful. Anything that updates periodically can become a problem. Bet to keep it limited to "on desktop view" or "on pressed". With the latter being the safest option.

Here's a clip of a corner of one of my desktops showing the widgets I have setup. The two octagonal ones are for network stuff, the square ones are for speed changes and battery checking. The "SpeedUp" button sets up a 800-1100 profile (very rarely used). The "Stock" button sets up the default 250-600 settings shipped by Nokia. The "900" button sets up my default 500-900 setting, which you can see is green (active). The last one updates on screen refresh with the current battery level.

Lots of options with QBW.