PHP 4.3.4 memory usage

I'm concerned with very steep jump the PHP 4.3.4 made in memory usage since 4.3.3. In 4.3.3 with configure options '--disable-debug' '--enable-inline-optimization' '--with-gettext' '--enable-track-vars' '--enable-mbstring' '--enable-mbregex' '--enable-mbstr-enc-trans' '--with-gd' '--with-zlib' '--with-bz2' '--enable-ftp' '--with-regex' '--enable-exif' '--with-iconv' the memory usage for PHP process was 4372 kB after running a simple phpinfo() script. This memory usage has been fairly consistent over many versions. However, the PHP 4.3.4 seem to have changed the trend big time. The same configure options for PHP 4.3.4 results in memory usage of 5572 kB. That's almost 30% more memory usage than 4.3.3. I am holding back on putting PHP 4.3.4 in production because of this issue. I've read that libraries for mbstring was rewritten for this version, and I wonder if that is the cause.