Open View - Set Font and select a True Type or Clear Type font like Courier New or Consolas and a font size suitable for you. Don't use a bitmap font available only in a few sizes as being defined with pixels instead of vectors This font can be a proportional or a fixed-width font. Do the same for View - Set HEX/Column Mode Font which must be a fixed-width font.

Read the post Font size for the File Tabs and the List Views for additional font/font size settings for file tabs and most list views. The post contains also links to font settings for Output Window and Find String List.

Font and font size for menus, dialogs, etc. are defined by the used Windows desktop theme in UltraEdit v16.30.

Open also Advanced - Configuration - Editor Display - Advanced and play with the font quality setting in this configuration dialog.

The term 4K UHD did not even exist as UltraEdit v16.30 was released December 2010.

The file changes.txt in program files folder of UltraEdit contains 733 lines between v24.20 and v16.30. And this file contains just a brief summary of important bug fixes, improvements and short information about new features. In other words many things changed since release of UE v16.30.

UltraEdit is shareware. So you can use UE v24.20 for 30 days before a license must be purchased for using it after trial period expired. This means you have the possibility to backup %APPDATA%\IDMComp\UltraEdit (copy to other folder, rename this folder, compress into an archive file, ...), uninstall UE v16.30, install UE v24.20 and use it with entire configuration recreated with default settings or existing configuration of UE v16.30 upgraded by UltraEdit v24.20. And when you think the new version is not worth the money, you can uninstall v24.20, reinstall v16.30, restore configuration of UE v16.30 and use again old version of UltraEdit.

cfp1, JPEG is good image format for paper scans or photos, but not for screenshots because its lossy compression adds a lot of pixel noise. For the future use PNG for screenshots which uses a lossless compression and is support by all applications supporting displaying or even editing images.

It is possible with UE v16.30.0.1003 to get a sharp display of syntax highlighted text as you can see on the attached PNG image.

The computer on which I made this screenshots has only a resolution of 1200 x 800 pixels. So the font size setting in Windows display setting was 100%. I have changed also the Windows desktop theme to Windows Classic as I do always on all my computers since Windows 95. And I have additionally disabled the color fading of active and inactive title bar by setting second color to same color as first color as it can be seen on looking on title bar of UltraEdit application window. I have disabled also ClearType as I don't like ClearType at all. If you use ClearType, you should run the ClearType tuner of Windows. I have also set once in the past at Control Panel - System - Advanced system settings on tab Advanced in group Performance after clicking on button Settings the option Adjust for best performance which disables all the features producing a stylish, but in my eyes unsharp display. And last but not least the color settings for document window area and syntax highlighting have been also configured to what is best for my eyes.

Consolas is designed for ClearType. So it is perhaps not good to use this font if ClearType is disabled in Windows configuration. There are lot of TrueType monospaced fonts and some are even fixed-pitch fonts (all characters have same width in all styles, regular, bold, italic and bold+italic). I used the font Courier New more than 7 years ago as I archived UE v16.30 which I restored from the archive to make this screenshot. I think this was the default font although not liked by many people. I had never a problem with this font.

It can be seen on the screenshot that there is a color fading on menu bar (toolbar was hidden to make the screenshot smaller), file tabs bar, and status bar. This color fading could not be disabled in UE v16.30. Later UltraEdit adapted its look better on Windows desktop settings. For example in UE v22.20 on same computer the entire UltraEdit window looks crystal clear with no color fading at all. Unfortunately with UE v23.00 the library used for GUI was changed once more for ribbon interface which brought back the ClearType look Microsoft favors also for their applications even on using Windows Classic theme as it can be see on the screenshot posted by me on post Icons are blurred in Classic mode with 64-bit UltraEdit version 24 on Windows 10.

Frankly, I am tired of explaining one UltraEdit user of hundred thousands of UE users every 3 months that purchasing a computer with an UHD display with physical dimensions < 24" for non graphic work was a very bad idea as those displays require a higher DPI value which means permanent increasing of fonts, icons and graphic elements by software rendering which most application, especially the old ones are not designed for. A computer with an UHD display with physical dimensions < 24" is good for viewing high definition photos, watching HD or UHD videos, playing HD or even UHD video games and limited for graphical work. But those displays are not designed for text editing work. Unfortunately many persons think good is what marketing of hardware selling companies persuade being good (more = better) and not what the physical conditions defined by resolution of human eyes and speed of image data processing of human brains really require. As I bought last time a notebook for myself, the most important properties were a keyboard making it possible to quickly write text and navigate in text, physical dimensions of display (not too wide to be able to use it in train from/to work), not too high resolution to be able to read text good without changing recommended DPI settings, battery working time of at least 4 hours. The keyboard layout excluded 90% of all notebooks on the market, the display 9% of the remaining 10%. Most notebooks are not designed anymore for people who really work with it.

Well, after looking once more on your JPEG screenshot zoomed in to see how each character is rendered although this is difficult because of the lossy compression, it looks like Sublime as well as UltraEdit v16.30 display the text identical. This comparison is difficult as the text in Sublime window is different to text in UltraEdit window. And additionally in Sublime a dark theme is used while in UltraEdit a light time is used for file window area. The font and font size should be the same according to what you wrote before and I could see on comparing the pixels of the characters. The text and color differences make an easy comparison of the two text windows pixel by pixel not really possible.

I think what you need to do to get a satisfactory display of files in document window area also with UltraEdit v16.30 on your UHD screen is adjusting the editor colors at View - Set Colors to a dark theme and the syntax highlighting colors at Advanced - Configuration - Editor Display - Syntax Highlighting for each used language to fit with the general editor colors.

I really think the light theme in UltraEdit is the main reason why you are not happy with the text display in UltraEdit on your UHD screen.

Sorry, but I don't have any UHD screen for testing. So I posted what I have configured giving you some hints. And I have my computers always configured for best performance for any application which means a spartan look which is good also for my brain. The image processing is done faster also by my brain if the windows don't have any style features not really needed to display the information I really need to process. I'm a programmer mainly for embedded controllers on which every microsecond counts. So I want always best performance with avoiding useless code executions and that is definitely the reason for optimizing also Windows PCs for best performance independent on used hardware.