For the correct functioning, some modules require regular technical maintenance. For example, watchdog module needs to remove old messages and search module needs to index site content.

Solution
Idexing
Decrease number of documents for indexing at one cron launching on the page of search settings. It’s better to run cron a few times a day.
Mailing
If you have simple news then it can …

So you should create subdomain for every user. For example,

http://mary.example.com 
http://kate.example.com 
http://jeff.example.com

This article is about storing information about site development. You will be able easy find it and make your corrections. Besides, sometimes you should pass this info to other web-developer.

This article will tell you how to disable (hide) block in a few methods: through block settings, PHP-snippet, SQL-snippet, etc.

Attention: You should immediately delete unused code because this could be dangerously. Do not leave back door for hacker!
You can run the code (snippet) in the following ways:

In block
In Execute PHP block …

This article is about re-saving all nodes on your Drupal-based site. You can wish to re-save nodes in the following cases:

This article is devoted to default input format for role or node type. Setting the default input format, you do not need to select format for every node created.

Problem
Get information about users who are currently on the site

So, you should create lines in your Drupal module as to plural work when translating to other languages.