There are always going to be little things that can help in small ways but probably the two most obvious reasons for lag are (a) quality of hosting and (b) including lots of images being served from remote servers. The latter is always going to make a significant and noticeable toll on performance – especially as with third party derived images there is no thumbnail available and the browser has to resize it before display.

So for a site with many large, remotely served images there is going to be lag and that is inevitable. Is there a possibility if encouraging your users to upload images to your site instead of linking to external sources?

Thank you a lot for your answer. 

But why it lags on simple press, and does not on other forums? I know other “non-SP” forums that have a lot of images being served from remote servers, and there  is not this lag. 

I can maybe encouraging my users tu upload images on my website instead of linking external sources, but I have to make this possible, and it’s not at the time. 

If by ‘other forums’ you mean stand-alone forum software such as vBulletin and phpBB etc., then they are always going to be a little different as they do not rely on the Wp backbone and are not influenced by other factors such as what WP plugins are active etc. It is also possible that some of the more commercial forums perform some complex caching. And – incidentally, based on your first post I have already open a discussion for us here on the possibility of doing just that. We can at least see if it would be plausible and useful.

Having said that – as a user of forums myself – I have encountered many that are slow loading with or without remote images being bought down. In many instances that will be caused by inadequate hosting – which is still probably the number one factor.

There are other more general things as well after hosting and remote images. for example keep both your use of WP and SP plugins to only the ones you need and remove any from the server not being used. The more individual forums you define the more data has to be processed (in some views) so ensure there are no more than you need. Keep the paging of topics and posts to a sensible number – obviously the more topics and posts you display ion a page – the longer it is going to take to process and render. And keep the database optimised. An unoptimised database can cause a lot of lag after a while as it struggles to return data.

Thank you a lot for the time you take to answer, and the quality of your post!

I take note of everything you said, I’ll talk to my developper, and give you feedback asap. 

please do…

I will have to clean my database from every little detail too, I think I will be able to give you the feedback Tuesday! 

okay, we will be here…