Conductive connection of localized surface plasmons (LSPs) was achieved by depositing a layer of continuous gold film onto the top surface of a matrix of randomly distributed gold nanoparticles (AuNPs) that were originally isolated on a glass substrate. Ultrafast spectroscopic response of such plasmonic nanostructures was investigated by femtosecond pump-probe detection technique. The transient-absorption data showed large redshift and broadening of the resonance spectrum of the conductively connected AuNPs with respect to the isolated ones. Such effects led to modulation on the evolution dynamics of LSPs in a transient transition spectral band. Making use of the temporal and spectral dislocation between the edges of transition band, we achieved much increased speed of the plasmonic optical switching effect.