@retrocop
I've been getting the slow/stuttery text input box, recently. I blame the animated adverts and just keep hitting the page reload button until the response to key inputs returns to normal.
Using Safari on a phone. Possibly too many pages open at once, especially multiple AB pages. Java does not run in Safari but does in IE/Firefox. If each tab is running its own script, loading ads even when a tab is in the background then your connection will be trying to download umpteen animated ads all at once and it slows to a crawl.
Firefox lets you disable Java and only switch it on when a favourite site says it needs it.
You could uninstall Java completely (quick way to find out which of your favoured sites need it).
Update it regularly, if you do use it. Search your computer for "Java Console" and use that to initiate the download/install.