external monitor

[widescreenparis]

What I am really interested in is the performance of the rMB when plugged into another monitor:

Are 2k youtube videos playing smooth (for example) ?
How about Netflix or big Power Point presentations?
General scrolling in Chrome with many tabs open?

I have experienced no performance hit whatsoever with an external qhd screen compared to the internal monitor.

 

[widescreenparis]

I have the 2015 rMB and I am using the HDMI connector to an LG Flatiron IPS235. I occasionally have issues connecting in clamshell, but for the most part it has worked well.

Would a 2560x1440 be that much of a different? The retina screen is obviously better and I'd like to be able to replicate that as much as possible.

I haven't bought a monitor in years, so any advice is appreciated!

A 25 inch QHD will be noticeably better than a 23 inch FHD but not night and day (about 20% more dpi) . However nowhere near retina resolution (still about half dpi so I guess that's 1/4th pixel density). As a result you will not benefit from HiDpi display settings and text won't be smoothed like with the internal screen. I was quite disappointed when I got mine and was even wondering if the hdmi adaptor was not bad. As far as I know there's not a ratio setting like on Windows to increase text size while keeping native resolution. 125% would probably be fine. If there's a way I would love to know, it's my first Mac and I'm not familiar.
The real benefit is screen real estate. That's still a lot of pixels.
I would love a 24 inch 4k screen but at 30 fps max that's not an option with the current MacBook.