[Samsung Galaxy Note 9 Guides, News, & Discussion] high_voltage:
Without going into too much tech details, the exynos cores them selfs are good, but their management is really bad. The problem is not entirely firmware/software (+if it was, it was going to be fixed for the time between s9/s9+ and note 9, in the mobile industry this is quite some time). It can be improved via kernel tweaks, but even then it can not match the snapdragon real world performance CPU wise. To simplify it even more - good cores, everything around them is bad, including their management. All of this leads to also big battery draining difference and a lot more endurance for the sd variant.

For the GPU... won't even talk about it, the adreno 630 is around 30-40% faster in games and with a lot better fps stability.

The exynos chip is also good, but it's a bummer that we actually pay more (1000 euro > 1000 us dollars) and got a vastly less superior SOC in the phone. To have a 1000 euro phone that has a lot of exclusive features and play games/ui is smooth like a 300 euro phone (xiomi poco) is one thing, but to have a 1000 euro phone that is less smooth and play games a lot worse than the 300 euro phone is another one.

Every year there was a difference between the exynos and SD variants, the recent ones - in s7 the exynos was faster CPU wise, better in battery life, better sound/DAC, smoother and with slightly slower GPU. In s8 the exynos is about on pair with the SD variant, better DAC, little bit worse battery life and a marginally weaker GPU (keep in mind that in 2017 there were no heavy games releases, this year it's a boom of them and the weaker GPU is bring to the spot lights).

This year the things escalated badly, the M3 cores are rushed and not finished (M4 will be the finished product and I think it will match the SD, BUT the gpu will be still mali bitfrost based and thus weak). Their management is done by another devision, not even in the same building as the team that engineered the SOC. The limitations are ignored and absurd clock speeds/voltage is applied, the SOC behaves better and drains a lot less with lower max clocks on the M3 cores - slower than SD. Snapdragon 845 on the other hand while didn't achieve massively better CPU scores, it actually improved quite a lot everything around them and the phones with it runs silky smooth and with good battery life. Peak performance is not all that matters in the constant clock speed scalings, task migrations, cores hotpluging and so on. The adreno 630 sustained performance is actually not that higher than 540, but the mali g72 mp18 in the exynos can't even match the 540, it's below it in peak and sustain - a lot below it and more so in real games. The note 9 will benefit more from the cooling in it's sd variant, actually.

Samsung even did try to somewhat hide it, all the reviews before the phone release were SD variant only. After it if we exclude the payed ones for exynos, the objective ones are all saying it's not only roses and smiles.

If who reads this can get the sd variant of s9/s9+/note 9 - do it, you won't regret it! It's the best phone/phones till now this year! The exynos is kinda... a lot left to desire from and can't be fixed in future updates. The next year the CPU I think will be on par with sd(and thus smoothness), but the GPU still weaker and by a lot. Samsung develops own GPU, but started late tbh, should had start it years in the past and now have the high end product like apple does.

Sorry for the long post, just wanted to say to all the people complaining for frame drops/not smooth/slower/lot worse gaming than expected on their exynos note 9 - you have the right to not be happy. Otherwise the SOC is still capable and phone good, just for that price compromise of the SOC itself and the performance is kinda... yeah, bitter tasted.