Memory exhausted when trying to browse tokens

Hi,

I have had this issue for a while but just kept increasing the php memory limit until the token list appeared.. Previously it was a case of adding a few MB to satisfy the requirements so I increased the limit to 1GB and moved on.. The site has gradually grown with more fields and a lot of content and today I wanted to change an entity label, I got the same error again but this time its saying it needs another 300MB of memory..

Why is this token browser such a memory hog?

Is there any way to reduce the memory demands?

Thanks..