Python host optimizations (bytes_to_hexstr, log formatting, _now_ms)

[lukasnee]

I found these bottlenecks while profiling my python application based on the min host using pyspeedscope. My application uploads firmware to a microcontroller and I was able to improve throughput by about 10% with these modifications.

Regarding commit perf(host): speed up bytes_to_hexstr up to 100x, here's quick benchmark test:

# test.py

import time

def bytes_to_hexstr_OLD(bytesequence: bytes) -> str:
    return "".join(f"{b:02X}" for b in bytesequence)

def bytes_to_hexstr_NEW(bytesequence: bytes) -> str:
    return bytesequence.hex().upper()

def timeit(f):
    start_time = time.time()
    f()
    end_time = time.time()
    return end_time - start_time

def test_case(bytesequence_size, run_count):
    input = bytes([i % 256 for i in range(bytesequence_size)])
    time1 = sum(timeit(lambda: bytes_to_hexstr_OLD(input))
                for _ in range(run_count)) / run_count
    time2 = sum(timeit(lambda: bytes_to_hexstr_NEW(input))
                for _ in range(run_count)) / run_count
    print(
        f"NEW vs. OLD {time1 / time2:.2f}x faster (bytesequence_size={bytesequence_size}, run_count={run_count})")

test_case(256, 1)
test_case(256, 10)
test_case(256, 100)
test_case(256, 1000)
test_case(256, 10000)
test_case(256*256, 1)
test_case(256*256, 10)
test_case(256*256, 100)
test_case(256*256, 1000)

python3 --version
Python 3.10.12
python3 test.py
NEW vs. OLD 4.44x faster (bytesequence_size=256, run_count=1)
NEW vs. OLD 63.05x faster (bytesequence_size=256, run_count=10)
NEW vs. OLD 60.77x faster (bytesequence_size=256, run_count=100)
NEW vs. OLD 77.76x faster (bytesequence_size=256, run_count=1000)
NEW vs. OLD 68.41x faster (bytesequence_size=256, run_count=10000)
NEW vs. OLD 127.16x faster (bytesequence_size=65536, run_count=1)
NEW vs. OLD 105.42x faster (bytesequence_size=65536, run_count=10)
NEW vs. OLD 122.96x faster (bytesequence_size=65536, run_count=100)
NEW vs. OLD 119.90x faster (bytesequence_size=65536, run_count=1000)