This is a default ENB bloom, tweaked to be more natural looking, with much wider falloff. Besides that, the first pass have also been modified to use 1024x1024 resolution rather than 512x512. Side effect of those tweaks is that it fixes most of the default bloom issues like square mipmapping artefacts, flickering (to some extend) and banding between the passes. I don't know what's the performance impact because I'm running F4 on rather hefty rig but from what I know it shouldn't be very heavy even with increased resolution.
Credits go to Boris for the shader, Wolrajh, for making 1.2 version tweaks, Modular Shader Library authors for the saturation code and Roxahris for his Gaussian/Kawase Bloom.
Default ENB Bloom:
Natural Bloom:
Default ENB Bloom:
Natural Bloom: