One thing I find when I move my training to the next level is just that - "a slight drop in performance" as well. This is where extra sleep, fluids and high quality foods can help. As well as energy products like that available from e-caps. http://www.e-caps.com/za/ECP?PAGE=PR...Y&CAT=HAM&OMI=
Products such as Race Caps Supreme, Anti-Fatigue Caps, and Liquid Endurance to name just a few I use.
Another great product I use is "Amino Vital" very quality product.