If it's short content that you need throughout the site, the fastest and easiest method would be to create new System Settings. Then you can access them anywhere with a setting tag:
If users need to be able to change the settings, ClientConfig from modmore makes it very convenient.
If you need to modify the data for some users, you can use User Settings or User Group Settings.
The second-fastest method would be pulling the data from a chunk with a chunk tag:
That's a good choice if the data is longer and/or needs to be edited.
I'm always hesitant about FastField because it replaces the MODX parser with its own.
MIGX is another option, but I don't know how it compares speed-wise to FastField or chunks.