This plugin enables you to easily add as many tags as you wish in one round, i tested it on my localhost to add 1000 tag and everything worked fine.

you can also specifiy a slug by using the following format tag,slug, a working example will be:

tag1
tag2,slug2

When you don’t specifiy a slug the tag name will be used as the slug, so in the previous example 2 tags will be inserted tag1 with tag1 as the slug,and tag2 with slug2 as the slug

You can also edit a function that will be used to modifiy the tags you insert, if you wish to edit that function go to the directory where this plugin was installed and then to the admin directory, open the filter-tags.php file and edit that function.

You will see that function in this plugin’s settings page, however it will only be read-only so you can make sure that the tags will be modified as you expect them to be.