What sort of education policy that can he execute in a short time and having the quickest effect to the national education?
You should understand by now that each time a new education minister is introduced, old policies will be ditched and replaced with a newer policy.

But sure, lets entertain the idea for now.
We all know he is very keen to re-introduce teaching of math and science in english. Very probably chance that will be among his earliest policy introduction.
Policies will set in to support the idea, and budgets will be put aside to establish proper execution of the policy all over the country.
Say in 6 months, a new minister is introduced for MoE.
Do you reckon the policy tun set in will stay? If we're being hopeful, that might happen. But past history has shown such policies won't last that long.

Perhaps what the education need is not a new minister, but a stable and consistent leadership/vision.

Yeah, well I'm just skeptical.
I do know Tun has the capacity, but he does not have the luxury of time.

I remember during the 90s, he envisioned for malaysia to have 20k engineers by 2020, so back then, they had sekolah menengah teknik all across the states. Almost every IPTA has engineering program now, but in the end....half-baked, over abundant of graduates but hardly enough quality.
PPSMI program was amazing though. Teachers get to enjoy new laptops, projectors, science lab materials, teaching allowances, courses in hotels. Slowly, the program losing fizzle once the funds dries up. No maintenance means the laptops eventually die past its shelf date. The lab equipments are mostly still there, but a husk of what it once was. Now I see the equipment are just used as decorations and piled behind the stores. The then education minister has no interest in pursuing the previous minister's policy and fell to the pressure of the nationalist community.