Gallery2 very slow with PHP5 (fine on PHP4)

Bit of a strange problem and my web host can't help, so am giving this forum a try. My installation of Gallery2 goes really slow when I run against PHP5 (v5.2.0), but is fine if I switch to PHP4 (4.4.8). My host allows me to toggle between the two versions, but I prefer to be on PHP5.

Does anyone know what the issue with PHP5 could be? Everything is fine in PHP4 - pages load quickly regardless of number of images, but when I switch to PHP5 I'm getting pages taking 30-40 seconds to load.

I'm currently running on PHP5 - the phpinfo is available here: http://www.sk7software.com/phpinfo.php

Any help would be appreciated.

Gallery URL = http://www.sk7software.com/gallery2/main.php
Gallery version = 2.3 core 1.3.0
API = Core 7.54, Module 3.9, Theme 2.6, Embed 1.5
PHP version = 5.2.0 cgi-fcgi
Webserver = Microsoft-IIS/6.0
Database = mysql 5.0.67-log, lock.system=database
Toolkits = Exif, LinkItemToolkit, Thumbnail, Gd
Acceleration = none, none
Operating system = Windows NT IIS06401 5.2 build 3790
Default theme = matrix
gettext = enabled
Locale = en_GB
Browser = Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.4) Gecko/2008102920 Firefox/3.0.4
Rows in GalleryAccessMap table = 61
Rows in GalleryAccessSubscriberMap table = 1280
Rows in GalleryUser table = 9
Rows in GalleryItem table = 1277
Rows in GalleryAlbumItem table = 34
Rows in GalleryCacheMap table = 0

(Edited for typo)