The assumption that someone is more intelligent just because he has an interest in sciencce is quite frankly ridiculous.
Orochimaru actually has the most stupidity feats in the entire manga in terms of battle. He is quite frankly stupid on the battlefield.
Firstly, training Hebi Sasuke and waiting until he was literally on his deathbed to take over his body. Now that was just silly, how the hell was he gonna defeat him in that state.
Against the third, he still managed to almost die, and lose his hands against an Old Third Hokage because of his silly little mind games and time wasting (toying around with the third). How can you do that and expect the guy (given who he was fighting) not to come up with a counter.
I won't even mention the stupidity of trying to take over Itachi's body on a whim instead of organising a proper ambush, perhaps with the aid of his sound 5 and maybe even Jugo and Kabuto.
Than, having gotten careless against the third (because of edo immortality) and ended up losing those edo's to a sealing jutsu, he goes and gets careless against Itachi because of supposed hydra mode immortality, and than loses to a fuin jutsu, AGAIN!
Any shinobi that loses to the same jutsu more than once clearly lacks something uptstairs.
You're not smarter than others just because you spent fifty years doing research. The only thing you might have is more knowledge than they do, but that doesn't mean you have a higher IQ.
Itachi, Kabuto, Minato, Hiruzen, Madara, Obito, Kakashi, Shikaku, and Shikamaru all clearly have higher IQ's than Orochimaru.