I don't know if this has been asked before, my searches didn't come up with anything but I may have just entered the wrong keywords, so let me explain the problem and my thoughts for a solution.
I play what I think is usually described as floating thumb, i.e. I don't anchor my thumb anywhere and I play what (in my early classical guitar tuition) was called rest strokes, so that the first and second fingers 'land on' the adjacent string after plucking a note. This has the usual benefit of keeping the 'landed on' string damped, but also acts as a stop so that the finger is ready to return to plucking.
Using this method, I find that I can play a fast series of notes on the A, D, G strings because my fingers are stopped by (and in effect bounce off) the adjacent string, but when I play on the E string, my fingers have nothing to stop them so they 'float' into mid-air and so I do seem to slow down a bit. An obvious suggestion would be to use a 5-string bass, then there is an additional string to act as a stop, but of course the problem would then simply shift to the B string.
What I am wondering about is adding a strip of wood parallel to the E string that my fingers can 'bounce off' when playing notes on the E string (not dissimilar to a long thumb rest). A diagram is probably the simplest way to explain this. The red mark on the picture shows where I would expect to mount the piece of wood.
I am wondering if this is something that anyone else has done, and what the negative effects of doing this might be (e.g. there might be some percussive effect though the body of the guitar as the fingers strike the stop). Any thoughts, suggestions, advice would be appreciated.
Geoff
