Initial minify very slow

Hi, I love your plugin, many thanks for sharing.
I am currently using 1.3 rc2 and it seems that the fancy url’s are working now.

However: the initial creation of the cache files is very slow:
– I am on a hybrid server, with 4gb ram, php has 512mb
– Every first pageload (after emptying cache) takes about 8-10 seconds, 90% of this is waiting for the bwp-minify files (in 2 parts, the head- and footer files)
– It does not matter if I add 5, 10 or 20 files per minify file. The resulting files are all less than 80kb

The second pageload is normal, i.e 1-1.5 seconds.

Is there a way to make the minifying more efficient?

Thanks!
ps: some server info:
WordPress Version:3.9.1
MySQL Version:5.6.16
PHP Version:5.4.28
PHP Modules:
Array
(
[48] => apache2handler
[8] => bcmath
[9] => bz2
[10] => calendar
[0] => Core
[11] => ctype
[12] => curl
[1] => date
[13] => dom
[2] => ereg
[38] => exif
[15] => fileinfo
[16] => filter
[17] => ftp
[18] => gd
[19] => gettext
[14] => hash
[21] => iconv
[34] => imap
[23] => intl
[55] => ionCube Loader
[24] => json
[3] => libxml
[25] => mbstring
[26] => mcrypt
[53] => memcache
[28] => mysql
[29] => mysqli
[30] => mysqlnd
[4] => openssl
[5] => pcre
[50] => PDO
[52] => pdo_mysql
[51] => pdo_sqlite
[31] => Phar
[32] => pspell
[33] => Reflection
[22] => session
[35] => SimpleXML
[36] => soap
[37] => sockets
[20] => SPL
[6] => sqlite3
[27] => standard
[39] => tidy
[40] => tokenizer
[41] => wddx
[49] => XCache
[54] => XCache Cacher
[42] => xml
[43] => xmlreader
[44] => xmlrpc
[45] => xmlwriter
[46] => xsl
[56] => Zend Guard Loader
[47] => zip
[7] => zlib
)

https://wordpress.org/plugins/bwp-minify/