[ethereum/go-ethereum] Sudden drop in TPS after total 14k transactions (#17447)

![https://gitlab.com/electronDLT/chainhammer/raw/master/chainreader/img/geth-clique-2s-gas40mio-RPC_tps-bt-bs-gas_blks21-65.png](https://gitlab.com/electronDLT/chainhammer/raw/master/chainreader/img/geth-clique-2s-gas40mio-RPC_tps-bt-bs-gas_blks21-65.png)

Details here:

* https://gitlab.com/electronDLT/chainhammer/blob/master/geth.md#results and
* https://gitlab.com/electronDLT/chainhammer/blob/master/chainreader/blocksDB_analyze_geth-clique.ipynb