Is Virtuemart 2 Broken?

[WebStuff]

I've tried several time to upgrade my store with only 200 or so products, so not vast, from Joomla 1.5.26 running VM 1.1.9 to Joomla 2.5 and VM 2 but each time after the upgrade the virtuemart component, apart from list categories, ends up causing a
"PHP Fatal error:  Allowed memory size of XXXXXXXXXX bytes exhausted (tried to allocate XX bytes)". I have tried various values for the php memory limit right up to 1000M which is ridiculously large for what it should need and still this happens. I've tried it in the php.ini file in the index.php file and anywhere else I can think of.
The last attempt to click on a category to view it's 12 products resulted in a server slow down as memory was swamped. When I killed the apache process it reported that 70 processes had been generated by selecting the product category.

Is it just me or is anyone else experiencing this type of thing.
The J1.5 and VM1.1.9 version of the site fair zip along taking only 1.58 seconds to list the same category's products.
Also it seems to have gotten worse as the version numbers have gone up. VM 2.0.10 seemed marginally better, it still took an unacceptable 38-54 seconds to pull up the products but only when I decided to upgrade VM first before Joomla and as this at least worked I didn't upgrade Joomla but when I upgraded to 2.0.12f. Same thing again.

Any help greatly appreciated.