Why do the swap fees for BTC frequently appear so significant?

Bitcoin network transaction fees make up the largest portion of the fees in an atomic swap with BTC. As Fastspot relies on two near-instant on-chain transactions for the HTLC (in and out), fees are chosen such that the transaction is confirmed within the next block. Depending on the current usage of the network, Bitcoin network transaction fees can easily be EUR 10 or more. The Bitcoin network usage varies over time and usually is lower on weekends, allowing for cheaper swaps at certain times. This also demonstrates the advantages of Nimiq as a next generation blockchain protocol where network transaction fees and thus fees for an atomic swap with NIM are close to zero.