It certainly is. Most of the reason modern computers don't feel instantaneous is actually a trade-off: old computers were less adaptive to change.
In old GUIs (e.g. Windows 3.1), many things—file associations, program launchers, etc.—got loaded from disk into memory once—usually at GUI startup—and then the state of those things was maintained entirely in memory, with programs that updated the on-disk state of those things either 1. also independently updating the in-memory state with a command sent to the relevant state-database-keeper; or 2. requiring that you log out and back in to see changes.
Today, we don't have everything sitting around loaded into memory—but in exchange, we have soft-realtime canonicity, where the things you see in the GUI reflect the way things are, rather than a snapshot of the way things were plus (voluntary, possibly missable/skippable) updates. Install a program that has higher-than-default-binding file associations? The files in your file manager will update their icons and launch actions, without the program needing to do anything.
There's ways to eat your cake and have it too—to have on-disk canonicity and instant updates—but this require a very finicky programming model†, so we haven't seen any GUI toolkit offer this, let alone one of the major OSes do so.
† Essentially, you'd need to turn your Desktop Environment into a monolithic CQRS/ES aggregate, where programs change the DE's state by sending it commands, which it reacts to by changing in-memory state (the in-memory aggregate), and then persists a log of the events resulting from those commands as the canonical on-disk state (with other aggregates fed from those to build OLAPable indices / domain-state snapshots for fast reload.) This gets you "Smalltalk windowing semantics, but on a Unix filesystem substrate rather than a VM memory-image substrate."
In old GUIs (e.g. Windows 3.1), many things—file associations, program launchers, etc.—got loaded from disk into memory once—usually at GUI startup—and then the state of those things was maintained entirely in memory, with programs that updated the on-disk state of those things either 1. also independently updating the in-memory state with a command sent to the relevant state-database-keeper; or 2. requiring that you log out and back in to see changes.
Today, we don't have everything sitting around loaded into memory—but in exchange, we have soft-realtime canonicity, where the things you see in the GUI reflect the way things are, rather than a snapshot of the way things were plus (voluntary, possibly missable/skippable) updates. Install a program that has higher-than-default-binding file associations? The files in your file manager will update their icons and launch actions, without the program needing to do anything.
There's ways to eat your cake and have it too—to have on-disk canonicity and instant updates—but this require a very finicky programming model†, so we haven't seen any GUI toolkit offer this, let alone one of the major OSes do so.
† Essentially, you'd need to turn your Desktop Environment into a monolithic CQRS/ES aggregate, where programs change the DE's state by sending it commands, which it reacts to by changing in-memory state (the in-memory aggregate), and then persists a log of the events resulting from those commands as the canonical on-disk state (with other aggregates fed from those to build OLAPable indices / domain-state snapshots for fast reload.) This gets you "Smalltalk windowing semantics, but on a Unix filesystem substrate rather than a VM memory-image substrate."