CS:GO VERY low framerate with only a few effects

Using LightDoF, MXAO, SSAA I drop from 150 FPS to 25 - 40 FPS, is this normal? Seems awfully low.

I would say that primarily that depends entirely on the settings you use with these effects but in general well depth of field and ambient occlusion (Whether it's standard SSAO or a custom effect such as MXAO.) will be pretty demanding, there's a little bit more to these than many of the lighter effects and it also depends on factors such as your current screen resolution.

I do not know much about these particular shaders myself though but in general with ambient occlusion there's usually a setting for the number of samples used and also distance for the effect, similarly depth of field can have distance settings and also extras such as simulated bokeh effect which can be pretty demanding compared to just blurring part of the image. (A dynamic effect with adaption will also require more calculation than a simpler background blur.)

Sorry if this seems a bit complicated but yes it is fully possible to completely tank the framerate even in older games if you go overboard with some of the settings in the more complex shaders.
(Or if the downloaded preset using said effects was configured like that to begin with.)

I'm confused because when I have those shaders loaded but not enable the frame rate still takes a massive hit as if reshade itself is causing the drop. Might been an issue with the configuration or something.