For a conventional start, you can stick with the default administration limit toggle for science in the game options.
If you prefer slower games with longer "tech eras," you might consider starting as TN with the admin limit on and a 25% research rate (this is my setup). This will give you an average of 10 to 20 years per tech up to the basic 5,000. However, reaching the Ion age, which is crucial for defence in Aurora space, could take around 200 years if you focus solely on propulsion tech. Beware that I do spend the TN RP bonuses, so I don't start from the ground up, making this a lesser steep curve.
While I respect different playstyles, I think in this case you are just hurting yourself. Conventional, plus anything below 50% research, is just too much in my opinion.
Let's delve deeper. Opting for the above strategy could confine you to Sol for approximately 300 to 400 years, assuming you neglect basic combat and civilian technologies. Your mineral supply in Sol would last at most 150 years. Assuming you roll a Sorium source to any of the eligible planets, developing the necessary technologies could add another 50 years (5,000 RP is the final tech but you require at least another 2 side techs between 1,000 and 2,000 RPs if you go for mobile harvesters, 5,000 if you want tugs) to your expansion plans. However, without it, you'll simply run out of fuel, as maintaining even basic operations like moving freighters becomes prohibitively expensive. So at that point, you either cheat and add a Sorium source via SM or yield to the infamous RNG Gods.
Of course, you can build hundreds of research labs, but then what is the difference between releasing 10 technologies all at once every 20/30 years compared to releasing the same 10 technologies within the same amount of time?
Now, imagine surviving this initial period only to encounter a hostile NPR 500 years into the game. You are facing an NPR with a gazillion RPs that sees your race as the apes at the end of 2001: a space odyssey*.
So, what can you do?
You can still lower your research rate to something that you are feeling more comfortable, for sure, but your best bet is probably to tweak the exploration rate (mine is set at 5%), this will slow down your spread and operations already. You can also introduce several in house rules and pace yourself. For instance, you cannot research multiple techs for the same group at the same time, you cannot have more than 30 research labs in total for your race, etc.
Another idea (mentioned before my post as well) is to cut your Population drastically. For instance, try starting with only 100/150 million people.
Overall, my feedback is that while longer tech area are nice, the whole game will still play at the same pace (mineral consumption, economy, fuel usage, NPRs generation) and limiting research rate is not as effective as you may think as there are other areas that would require proper settings for you to enjoy the game and play it on levelled field once NPR or Spoilers appear. It's true that human players always have the upper hand over NPRs, however, tech is a major factor in Aurora (and real life).
*Note: I am unsure if starting RP points receive a cut by the malus in research rate when generating a new NPR in game, so that may not be an issue. I don't think so, as while the generation accounts for your RP (which were limited by the malus) I am pretty sure that in game time is part of the generation code. Anyway, I do know that NPR research rate is the same as yours once they spawn, along with all other parameters. Overall though, the handicap will impact more the NPR faction than the player at that point, further compromising the experience.
