Taxonomy: Too many tags? I have a serious problem with the core's taxonomy module (Drupal 7): I have some vocabularies containing all together about 140,000 tags. I do not show these tags anywhere or use them for filtering or anything like it. At this point they are used only for a solr search index. It would be nice to show all nodes that have a certain tag as well, but I am not using this feature yet.
Each node does not have more than 20 tags. 

But nevertheless the taxonomy module eats all my memory so that the whole site is broken. I get the message 

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to     
allocate 75 bytes) in .../modules/taxonomy/taxonomy.module on line 1022 


Does that mean, taxonomy module is not capable to deal with vocabularies that big? What am I supposed to use instead of taxonomy module to deal with big vocabularies?
Nope, the taxonomy module can handle as many terms-per-vocab as your hardware will allow it to (within some reasonable theoretical bounds I'm sure, but certainly 140,000 terms would not be too much these days).

The 'problem' is in your server configuration. Quite simply you don't have enough available memory for the taxonomy module to process as many records as it needs to.

Try increasing the PHP memory_limit setting gradually and hopefully you'll be able to come to an acceptable compromise between your available memory and the size of your vocabularies.

Just to preempt what I think your response will be - you're already allocating 256MB, which might be a large (even outrageous) amount of maximum memory to give to a single PHP script, but the fact that you're getting out of memory errors means it's simply not enough for your site and needs to be increased (unless you want to optimise the core taxonomy module which I don't think would be much fun).

If you're on shared hosting, the first thing to do would be to get the site on a dedicated server/VM. That should make a good bit of difference.