[Desire Android Development] fred_be9300:
I installed this recently too. There is a bit of lag here and there, but then that's very subjective, and depends on number of apps installed, and services running permanently (like viber, skype, whatsapp, talk, ...)

I have 2 class4 16gb cards, and recently compared their performance (using CrystalDiskMark on pc). There were some noticable difference, especially for random (non-sequential) writes of smaller files. (see results below)

So one thing you could do, is check your sdcard performance.

Other things I did was play with

* the Governor... I forgot what it comes with default, but switched to Smartassv2, and then to "interactive". Also overclocked a bit (1075200). I used to have more, but had a handful freezes in 1 week, so dropped down.

* the kernel: switched (this morning) to droidzone kernel "2012June18" It seems snappier, but I'm pretty sure that's because the phone just rebooted. Need to give it a few days

* I removed some stuff from /system (ringtones, wallpapers) and created a custom hboot partition - to add another 25mb to /data/data compared to cm7/r2 [this doesn't change speed, but gives more space for my app's data)

* note: this rom doesn't seem to set the SDCARD readahead - many others do as it is believe to increase sdcard read speed. You could add

echo "1024" > /sys/devices/virtual/bdi/179:0/read_ahead_kb; to anyone of the init.d scripts.

Note: 4EXT recovery is (by many) believed to provide better sdcard repartitioning and formatting results (correct alignment). The touch recovery is pretty sweet, I switched to it recently coming from some 2.5.1.8 (or so-ish) version. It's a nice upgrade, anyway. On the other hand, (per default) it makes nandroid backup in a format that's different from CWM (I think), so you need to stick with it.

-----------------------------------------------------------------------
CrystalDiskMark 3.0.2 (C) 2007-2012 hiyohiyo http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 19.335 MB/s
Sequential Write : 5.642 MB/s
Random Read 512KB : 18.946 MB/s
Random Write 512KB : 3.131 MB/s
Random Read 4KB (QD=1) : 3.969 MB/s [ 969.1 IOPS]
Random Write 4KB (QD=1) : 1.133 MB/s [ 276.6 IOPS]
Random Read 4KB (QD=32) : 4.779 MB/s [ 1166.7 IOPS]
Random Write 4KB (QD=32) : 0.911 MB/s [ 222.3 IOPS]

Test : 50 MB [G: 94.9% (14.1/14.8 GB)] (x5)
Date : 2012/11/12 22:34:24
OS : Windows XP Professional SP3 [5.1 Build 2600] (x86)
transcend 16gb class4 microsd

-----------------------------------------------------------------------
CrystalDiskMark 3.0.2 (C) 2007-2012 hiyohiyo http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 18.738 MB/s
Sequential Write : 6.042 MB/s
Random Read 512KB : 18.807 MB/s
Random Write 512KB : 1.235 MB/s
Random Read 4KB (QD=1) : 2.938 MB/s [ 717.3 IOPS]
Random Write 4KB (QD=1) : 0.514 MB/s [ 125.4 IOPS]
Random Read 4KB (QD=32) : 3.503 MB/s [ 855.2 IOPS]
Random Write 4KB (QD=32) : 0.744 MB/s [ 181.7 IOPS]

Test : 50 MB [G: 82.6% (11.4/13.8 GB)] (x5)
Date : 2012/11/12 22:51:13
OS : Windows XP Professional SP3 [5.1 Build 2600] (x86)
sandisk 16gb class4 microsd