hey

memcache performance stinks in Cache Router.
please consider "stealing" the new/whole code from Memcache API (memcache) module.

here's some data i collected:

APC on by default, Memcache API on, AuthCache on, Drupal cache on:
> Mem:   1019180k total,   864564k used,   154616k free,    34412k buffers
> Swap:   262140k total,    12844k used,   249296k free,   528036k cached
>
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>  5514 galaxy-n  20   0  552m 164m  78m S    0 16.5   0:03.46 php5-cgi
>  5227 mysql     20   0  248m  77m 5448 S    0  7.8   0:03.84 mysqld
>  5287 nobody    20   0 31476  15m  712 S    0  1.5   0:00.03 memcached
Session - logged in, manager:
> Page execution time was 421.5 ms. Executed 93 queries in 15.78 milliseconds.
> Memory used at: devel_init()=0.76 MB, devel_shutdown()=20.53 MB.
Session - anonymous:
> Page execution time was 217.63 ms. Executed 53 queries in 9.98 milliseconds.
> Memory used at: devel_init()=0.75 MB, devel_shutdown()=11.87 MB.

APC off by default, Memcache API on, AuthCache on, Drupal cache on:
> Mem:   1019180k total,   854840k used,   164340k free,    73244k buffers
> Swap:   262140k total,    12844k used,   249296k free,   457740k cached
>
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>  5973 galaxy-n  20   0  557m 100m 8572 S    0 10.1   0:20.65 php5-cgi
>  5720 mysql     20   0  244m  80m 5708 S    0  8.1   0:06.38 mysqld
>  5779 nobody    20   0 36600  20m  712 S    0  2.0   0:00.06 memcached
Session - logged in, manager:
> Page execution time was 828.33 ms. Executed 93 queries in 16.37 milliseconds.
> Memory used at: devel_init()=4.68 MB, devel_shutdown()=73.8 MB.
Session - anonymous:
> Page execution time was 621.42 ms. Executed 53 queries in 10.96 milliseconds.
> Memory used at: devel_init()=4.66 MB, devel_shutdown()=63.92 MB.

APC on by default, CacheRouter on (apc), AuthCache on, Drupal cache off:
> Mem:   1019180k total,   852432k used,   166748k free,    73620k buffers
> Swap:   262140k total,     9632k used,   252508k free,   479092k cached
>
> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 20150 galaxy-n  20   0  551m 165m  79m S    0 16.6   0:02.91 php5-cgi
> 19902 mysql     20   0  264m  76m 5432 S    0  7.6   0:04.36 mysqld
Session - logged in, manager:
> Page execution time was 450.48 ms. Executed 92 queries in 17.79 milliseconds.
> Memory used at: devel_init()=0.73 MB, devel_shutdown()=20.49 MB.
Session - anonymous:
> Page execution time was 211.47 ms. Executed 54 queries in 10.77 milliseconds.
> Memory used at: devel_init()=0.72 MB, devel_shutdown()=11.73 MB.

APC on by default, CacheRouter on (memcache), AuthCache on, Drupal cache off:
> Mem:   1019180k total,   999240k used,    19940k free,    70172k buffers
> Swap:   262140k total,    10936k used,   251204k free,   541336k cached
>
> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 27257 galaxy-n  20   0  554m 166m  78m S    0 16.8   0:35.85 php5-cgi
> 27009 mysql     20   0  264m  76m 5536 S    0  7.7   0:04.19 mysqld
> 27068 nobody    20   0 38528  22m  712 S    0  2.2   0:22.00 memcached
Session - logged in, manager:
> Page execution time was 1674.38 ms. Executed 95 queries in 16.4 milliseconds.
> Memory used at: devel_init()=0.77 MB, devel_shutdown()=21.96 MB.
Session - anonymous:
> Page execution time was 1225.27 ms. Executed 54 queries in 10.48 milliseconds.
> Memory used at: devel_init()=0.76 MB, devel_shutdown()=12.54 MB.

APC off by default, CacheRouter on (apc), AuthCache on, Drupal cache off:
> Mem:   1019180k total,   782616k used,   236564k free,    76500k buffers
> Swap:   262140k total,     9624k used,   252516k free,   408248k cached
>
> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 21640 galaxy-n  20   0  552m  96m  10m S    0  9.7   0:09.92 php5-cgi
> 21392 mysql     20   0  264m  76m 5476 S    0  7.6   0:03.88 mysqld
Session - logged in, manager:
> Page execution time was 845.46 ms. Executed 92 queries in 18.35 milliseconds.
> Memory used at: devel_init()=4.52 MB, devel_shutdown()=73.48 MB.
Session - anonymous:
> Page execution time was 543.44 ms. Executed 54 queries in 9.51 milliseconds.
> Memory used at: devel_init()=4.51 MB, devel_shutdown()=63.61 MB.

APC off by default, CacheRouter on (memcache), AuthCache on, Drupal cache off:
> Mem:   1019180k total,   817072k used,   202108k free,    77144k buffers
> Swap:   262140k total,     9624k used,   252516k free,   406108k cached
>
> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 22124 galaxy-n  20   0  557m  99m 8376 S    0 10.0   0:20.83 php5-cgi
> 21870 mysql     20   0  264m  76m 5512 S    0  7.7   0:04.12 mysqld
> 21929 nobody    20   0 37440  21m  712 S    0  2.1   0:10.96 memcached
Session - logged in, manager:
> Page execution time was 1880.83 ms. Executed 92 queries in 18.22 milliseconds.
> Memory used at: devel_init()=4.58 MB, devel_shutdown()=74.98 MB.
Session - anonymous:
> Page execution time was 1438.02 ms. Executed 54 queries in 10.38 milliseconds.
> Memory used at: devel_init()=4.57 MB, devel_shutdown()=64.44 MB.

Comments

notice the time it takes pages to load when Cache Router is configured with Memcache.

global APC on:
Logged in - Page execution time was 1674.38 ms. Executed 95 queries in 16.4 milliseconds.
Anonymous - Page execution time was 1225.27 ms. Executed 54 queries in 10.48 milliseconds.

global APC off
Logged in - Page execution time was 1880.83 ms. Executed 92 queries in 18.22 milliseconds.
Anonymous - Page execution time was 1438.02 ms. Executed 54 queries in 10.38 milliseconds.

more information in this discussion, with attahcments (odt and pdf)
http://groups.drupal.org/node/135989