I definitely agree about low survey speed. My current AAR campaign is at all default speeds as I wanted a lot of quick action, but most of my campaigns I have played around with 25% or 10% survey speeds to incentivize large survey fleets and making system surveys a full scale military operation instead of one ship flying around praying not to get killed by angry NPRs.
With tech speed I have been considering a house rule restricting the number of labs per scientist to much less than their actual maximum, e.g. 20% of maximum. I do like the feel of 100% tech speed in terms of building a realistic (to me) multi-generational fleet, but I also want to actually play with the low tech levels in the process. Restricting, say, the skilled P&P scientist with 25 admin skill to only, say, 5 labs prevents rushing the propulsion techs while keeping a good overall rate of progression - and might force spending more time in early tech lines usually relegated to the Ion+ era.
Don't get me started on house rules for labs or even industry...
When a lab is built it is always designated to ONE specific area of technology... I could change labs to another category later on but I would need to take two, destroy one and then transfer the other to a new field.
Scientists work in specific fields and there are limits to how many labs can switch between scientists in a single year even within the same technology area. The easy math here is a scientist can only receive its admin rating divided by 10 rounded up in a year, they may loose any amount. If they switch into a completely different field within an area (say researching railguns and then missile launchers) after a project is done they can only retain admin rating divided by 5 labs, the rest have to be allocated elsewhere.
I do similar thing with all industry too... no planet may switch more than roughly 10% industry capacity per year between projects. only if there is some sort of emergency can this rule be extended to about 20% in a year.
I can't just switch ordnance and fighter industry on and off for example either... they to can only add or remove about 10% a year unless there is some emergency. So... if my ordnance industry is idle on a world it would normally take me a decade to get up to full production again or five years if there is a war going on.
Sometimes when the military want a new type of ship or modernize an old one I have to write up a proposal for myself for the politician to accept... I better do a good job convincing myself it is worth the time and money to do just that ship and not something else... perhaps the politicians are more interested in completely other things and cut the military budget. I probably am a bit schizophrenic sometimes, surely feels that way... but it probably just are the role-player side that want to get out and play.
Limitation and role-play is what this game is all about in my opinion... so just go nuts...