The time is not accidental. Coptic worship is built around preparation, Scripture, intercession, offering, thanksgiving, consecration, Communion, and dismissal. It is a full liturgical action, not a short talk with songs around it.
Why it takes time
The Church gives time to God because the Liturgy gathers the whole life of the faithful into worship. The readings are not filler; they place the parish under Scripture. The litanies are not delays; they teach the Church to pray for peace, the fathers, the sick, the departed, the place, the waters, and the needs of the world.
The Eucharistic prayer also takes time because the Church gives thanks, remembers Christ’s saving work, and asks the Holy Spirit to sanctify the gifts.
If you cannot stay the whole time
Come for what you can and leave quietly if necessary. If you are exploring seriously, try at least once to stay through the end so you can see the service as a complete whole.
When you need to leave, avoid leaving during the Gospel, the Eucharistic prayer, or Communion if you can. If you are unsure, wait for a natural movement in the service.