If you are importing them into Photoshop with the intention to keep them editable your file will soon become unmanageable, text is the biggest Photoshop enemy and will eat up your RAM super fast.
You can do several things, make sure the text is perfect and no typos are present, basically, that it won't have to be edited anymore. Then import each line as a rendered object and in a separate layer, after you are done select all the layers and use the align command, that will center them according to the exact size of the overall box formed by selecting all the layers.
the second option would be to manage all text in Illustrator, (which will also have degrade performance with excessive text) and then export to psd, either with the text still editable or rasterized, your choice.
Finally, you can edit all your text in Indesign, super fast and simple, since the program is designed to work with huge loads of text and then export a pdf file, that file can be opened in photoshop and continue to be further treated in there.