The user interface gets/sets/syncs settings with the engine running in the background which acts as a server . The engine server socket port is between 1900 - 2500 range. If there is a firewall blocking this port, then the User interface will slow down a lot. You will see this error listed many times in the debug log. The bolded entries are the important ones to check in the error stack trace below.
May 7, 2020, 10:46:22 PM java.net.ConnectException: Connection refused: connect
at java.base/java.net.PlainSocketImpl.connect0(Native Method)
at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:101)
at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
at java.base/java.net.Socket.connect(Socket.java:591)
at java.base/java.net.Socket.connect(Socket.java:540)
at java.base/java.net.Socket.<init>(Socket.java:436)
at java.base/java.net.Socket.<init>(Socket.java:213)
at com.hitek.engine.core.EngineLauncher.getEngineReply(EngineLauncher.java:154)
at com.hitek.gui.core.TaskTableDirectoryModel.getObject(TaskTableDirectoryModel.java:315)
at com.hitek.gui.core.TaskTableDirectoryModel.getValueAt(TaskTableDirectoryModel.java:237)