Yes, you will gets tons of delays and bad performance from such a system (automated conversions).
That is the reason that HDL engineers are well paid, but then again it takes a couple of years practice to be a good HDL coder. There is no such thing as "free meal" with automated converters.
On the other hand if you use simulink model instead of matlab .m scripts as an entry language, then the translation to hardware is easy and straightforward. And even the automated tools can do a good job.
That is why I told you guys to use "DSP builder" for simulink. But somehow you do not believe me.
No problem, you are young, you will learn (the hard way) :)
Good luck transforming .m into c and c into HDL.