Your comments

Well, okay. But still maybe in the future updates? 
If there's no reason for scroll at the moment, it shouldn't be there.
The interface feels more solid when such details are carried of.
Well, I mean that you could replace that jumpy text in the beginning. You can set the alpha to zero until that first 100 lines are highlighted. 
So that will not be too much delay for the user if you wait for the first 100 lines only.
I tested on iPad 2 and new iPad highlighting takes less than a second for 150 lines text. Probably the original iPad is a little bit slower, but anyway from the UX point of view it's much better to show ready text than push plain text and update it to highlighted in 0.5sec after it appears. Trust me :)

PS well, actually if it's hard to implement, just don't worry. Sometimes I'm maniacally attentive to details.
Am I right that you advice to remove buttons "Upload This File" and "Download Latest" with one button Sync, and Textastic will handle the conflicts itself, asking for your decision when necessary?

E.g. Textastic saves the timestamp when the file was downloaded or last time synced. And if this timestamp is the same as the last modification time of the remote file (when you press sync) Textastic just uploads your file to the server. And vice versa. 

The situation Textastic asks user what to do if smb edited file remotely and locally at the same time (timestamps doesn't match).

PS also for the future there could be some File Merge functionality.
That's really important feature for every code editor and it will be just great if you implement it.
But what if you want to upload that PDF or any other file to the server using Textastic?
That could be handy to have "Open In…" for that.

And what is the reason of keeping 10+ PDF Readers on your iPad?
On the screenshot the first line of copied text doesn't have tabs because I copied it with no tabs and I placed it to the line with no tabs. 

The same is if you try to paste it to the more tabbed line, e.g.