UPDATE
I'm trying from microSD to microSD and it is fast enough (500 KB/sec or sometimes 4 MB/sec). Average: 1.19 MB/sec.
So the problem appears to be the internal memory.

I want to leave my original message so it can help someone having the same problem as me.

Now I will try to use a partition in microSD as swap to free a few work of the internal memory.

Maybe the phone of my wife have a more faster internal memory.

Bye bye.

ORIGINAL MESSAGE
I was tired about my N900 slowdown and noticed what the worst slowdown is produced when it is doing some related with I/O operations.
Recently I have a microSD (Patriot 16 GB Class 10) and my N900 is slow too copying files to it?? It appears to don't care if I use the best memory in the world or the worst one.
I just buy that because I had a slowdown problem in I/O operations and I guessed (searching in this forums, internet and so) what the problem is the internal memory. But now I can see that not. That is not the problem, there are some other kind of problem.
I get a throughput of near 1 Mbytes/sec in the first 2 or 3 seconds but next it continuously drops to near 0 and sometimes it shows 15 KB/sec only but is sustained in 0.
It takes more than an hour to only copy 250 MB of a few files from internal memory to microSD. The same happens if I try to copy in the internal memory. ??? what??

The mini CPU load indicator (it that displays a little bar) is always at max.
Conky shows nothing about CPU load. CPU usage is just at minimum. I/O activity in conky anyway there are nothing special (0 bytes per second or something momentary 1 MB but it keeps in 0 just like what I see in the status copy of mc). But Load in system is 6 or more. ???
No one application is using CPU, of course, CPU just indicates a low usage. XOrg sometimes use 8~12% cpu. But I'm not copying files with XOrg lol (of course). Swap memory too is in low usage (less than 400 MB). Maybe here are some problem? mc that is the program who is copying just don't use CPU at all.
But the little cpu usage bar indicator shows always at max.
Of course the N900 is slow when it try to open a new application. But the already opened applications works well.

And when I copy files using the USB in the PC. Using the N900 connected to USB in Mass Storage mode. The throughput is sustained near 10 MB/sec reading and 5 MB/sec writing. So?? wtf?? From Internal memory to Computer and the same for microSD (inside the N900) using Mass Storage mode works great/faster.
I'm actually copying from Internal memory to microSD and it just copies at sustained 4,7 MB/sec. In mass storage mode using the computer. So the memories not are slow at all. There are some other thing slow in my cell phone that just becomes slow when I'm doing I/O operations slowing all I/O.

I'm using PR 1.3 updated (no extras-devel). But I noticed this problem of slowdown I/O first in the stock version of my phone software (1.2). So I updated next. I noticed a little improvement but the I/O slowdown is still present.
Don't matters if I change to stock kernel or not. For now I'm using 2.6.28.10-power47. The same I/O slowdown happens.

But my wife have another N900 and that slowdown is not present in her phone! Her phone works very well in I/O operations!! Using the same version of software. It is faster than mine!

The only difference in my phone and her is what her is more new version. Maybe that is a hardware failure from older N900. If so, I'm lost now I cannot solve it only buy a newest one.

Both cpu tests (nbench) get the same results (in her and mine). But her phone is more faster than mine. I don't understand how :S
It opens the applications much faster. The scrolling and animations are more smoothing too. That just make me fall over her phone, but she don't wants that :P
So I must use the mine so slow

lol

But, I want to solve this mystery. Maybe the swap partition? Maybe something with internal hardware? Or some software (kernel param or something) option that need my version of hardware to works correctly?
Some bug in hardware what need a workaround in software? An answer please!! God!! lol

I don't know what is it. But I know that I cannot just use my phone to copy anything inside (I need an external PC for that, lol, damn phone it suppose to be a micro pc, or not?).
I will try to do some tests and to use some scripts / recommendations to try improve performance in my phone. Maybe that can solve the problem... I hope...

Bye and thanks for reading.

PD: If nobody happens this then I have a damaged phone (because I just buy it used not new). So I will must "drop" it

The only thing that comes to my mind might be this:

http://talk.maemo.org/showthread.php?t=72789

There seems to be a bug in the kernel module for mmc access which seems to break transfer to certain class 10 microsdhc cards.

I had a class 2 card in my phone, worked perfectly. I then changed to a class 10 card, I also wanted to partition the card in order to get an external swap partition. Meagre I/O, and a lot of I/O errors in dmesg.

After applying the patch in the linked thread, everything works perfectly.

In your case, I would first check the messages of dmesg. When you see a lot of I/O errors there after transferring files, you might consider applying this patch. As you are using kernel v47, make sure to use the right kernel module, linked here:

http://talk.maemo.org/showpost.php?p...8&postcount=10

I use
If you install the sysstat package, you can run
To look at I/O statistics.

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
mmcblk1 0,24 0,13 0,05 0,05 0,67 0,73 27,88 0,03 295,24 49,63 0,50
mmcblk0 0,00 0,17 0,02 0,00 0,09 0,71 62,13 0,00 23,65 12,59 0,03

wkB/s: kilobytes written per second
avgrq-sz: Average request size. As mmc/sd style media hates non-sequential writes, this should ideally be closer to 500 than 4.
%util: how busy this storae device is

I have same problem.
In dmesg i have i/o errors, including -101 errors.
I copy files from emmc to sd card.
Errors on dev: mmcb1k0p1

How can I path new versions of power kernels? or how get older version like v47? i asume that my problem is related with mmc driver bug, a i right?