Measure frequencies fast and precise
You said "I need to measure frequencies between 25kHz and 150kHz", but you didn't say anything about the max rate of frequency change. Assuming the frequency is changing slowly you could get the result "almost" instantly.

Arrange the timers as free-running counter. On each incoming front of measured signal load current value of the free-running counter into memory. Store last, say, 64 values. And at the moment when you need to know the frequency - just subtract some previous N-th value of the free-running counter from the last value. That would be the number of oscillator ticks between the last front and N-th front back in time of measured frequency.