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One of the biggest critics made to bitcoin so far are the expensive costs that a transaction can reach when the network is overloaded. However on long run, specialists and enthusiasts defend it's not a problem, as the hardwares, responsible for the mining operation are evolving, getting more powerful to process the transactions faster and with less effort.
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I think it's worth pointing out that processing the transactions is not what requires a lot of energy resources. All the transactions put in a block can be processed by any node in a fraction of a second without spending any significant resources. What requires energy is proving to the network of nodes that it's your node that deserves the block reward with all the transaction fees included. I mean, mining tools are not evolving in order "to process the transactions faster and with less effort". They are evolving to solve the computationally difficult problem, namely that the SHA-256 hash of a block's header(hash of the previous block, version, difficulty target, timestamp, Merkle root, and nonce) was lower than or equal to the network target.
I understand that many people here know this without my explanation, but judging by some replies and by the OP article itself, I thought it needed some clarification.