Find mosfet by frequency?

[nandoanalog]

 
 How do you guys know if a mosfet can turn on and off quickly enough for the job at hand?

[DimitriP]

In your selection process, where does t_on and t_off come into play ?

[nandoanalog]

So, with all things sorted out, gate capacitance is the enemy?
Is there a way to pull current very quickly from the gate once the signal is low?

Would this work?
The 1pF capacitor is there as a representation of gate capacitance.

http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.200277308269968+50+5+50%0Ag+400+368+400+400+0%0AR+384+16+432+16+0+0+40+12+0+0+0.5%0A162+384+16+384+96+1+2.1024259+1+0+0%0Ar+384+96+384+128+0+1000%0AR+112+192+80+192+0+2+20+5+5+0+0.5%0Af+320+160+384+160+0+1.5%0Aw+384+128+384+144+0%0Aw+384+368+400+368+0%0Aw+112+160+112+192+0%0Ar+320+160+320+192+0+1000%0Ac+320+192+320+224+0+1e-13+9.598073174038761%0Aw+384+176+384+224+0%0Aw+320+224+384+224+0%0Aw+384+224+384+368+0%0Ad+112+160+144+160+1+0.805904783%0Aw+320+160+256+160+0%0Aw+144+160+256+160+0%0Af+224+208+256+208+1+1.5%0Aw+256+160+256+192+0%0Aw+256+368+384+368+0%0Aw+256+224+256+368+0%0Aw+144+208+224+208+0%0Aw+112+192+112+208+0%0Aw+112+208+144+208+0%0Ad+320+192+256+192+1+0.805904783%0A

[nandoanalog]

 I'd like to drive 5W ir LEDs somewhere below 100 khz. Most likely below 50khz...