The system expels me continuously by repeatedly requesting my username and password, what may be happening? It is notorious mainly in the mobiles and the majority of my users use mobiles.

HI, Lucio.

Thank you for contacting us.
This may be caused by browser of Joomla! caching... or cookie settings.
Please, make sure that you disable caching in Joomla! and your cookie configuration is correct (or disable it).

Dear Sirs, I have it configured like this, is it correct?

I would like to optimize my website and be as fast as the demo of PCs, I only have 650 registered and only about 20 online on average and the web gets very slow
demo.jomsocial.com/

HI, Lucio.

Disable System Cache. It probably cause teh issue.
If you want your site fast you'll need to make sure that site is not bloated by extensions or spared code... like heavy template.
This may also depends on server you host your site on.

In the end I did not understand, here I have a dilemma, disable the cache or do not disable it?
It is a contradiction, lines above tell me to disable it and here that if I disable it I will have problems.
On the other hand my web has surpassed the 6K of visits and it becomes very slow therefore my hosting provider tells me to enable the cache, please I need that they help me.
I do not have extensions, I only have the Jomsocial and the cometchat is everything, but my server gets saturated frequently. Or hangs up and I get some screens that I attached. Thank you

HI, Lucio.

In my latest reply there is no contradiction :)
Cache is used to cache some content. This do not apply to db content.
You should rather use gzip to speed up site load - not cache.
Joomla! cache cause too many issues with session and content display (it's delayed).

First of all, please, provide me your site credentials so I could make some checks:

1. Edit your first post.
2. Click switch below main text field: prntscr.com/fk3hdg
3. Provide your site details: backend URL, admin credentials and FTP: prntscr.com/fk3hwz
4. Let us know that you provided credentials by posting in the same thread.

Error displaying error page means that there is no error page to display - that's a Joomla! issue.
You should also check your server error log in cases like that - they may contain additional informations.