There are several ways to speed up the insertion of a transaction.
Create a transaction template for your frequent transactions.
You can manage them in the "Preferences" page, "Transaction templates" section.
To use your transaction templates, press the star in the top menu of the "New transactions" page.
Select a default account in the "Preferences" page, "New transactions" section.
This account will be preselected for each new operation, but you can still change it.
You can set a default account for incomes and one for expenses.
Reorder the categories to have the more used at the top of the list.
You can do it in the "Preferences" page, "Categories management" section.
Press for 1 second on a category and drag it to reorder that category.
Widgets (Android app only)
In the Android app, you can enter the transactions from the 3 widgets available.