Investigate benchmark slow-down

[tolauwae]

After adjusting the benchmarks for the new project structure, and adding edward benchmark (c85bc8ee76e71e7ec05ed13fe9b4463ff0c1aa8c), the benchmarks are 5 to 6 times as slow.

[tolauwae]

Rerunning the benchmarks with the same setup (arduino-cli and arduino-esp32 v2.0.3) gives slightly slower results as before (compared to SPE results).

benchmark	SPE results (v0.1.0)	v0.2.0	new results (v0.1.0)
catalan	139.3782611610004	738.6412682709997	196.8789142679998
fac	48.967824086999826	237.34346405700126	63.28970348300027
fib	66.33100416200068	367.9925268250008	98.20201183300014

Conclusion: arduino-cli does probably cause a slow down, but cannot be the main cause. The project restructure must have introduced a bug which is the main cause.

[tolauwae]

Executing the catalan benchmark with the emulator gives the following performance profile:

How representative this is, is in doubt.

[tolauwae]

IO fflushes were the culprits. Removed in ac669055e1e49e043b3d568a269bda1a776accae.