s <- "שללללוווווםםםם ......... שללללוווווםםםם"
gsub("(\\p{Hebrew})\\1{2,}", "\\1", s, perl=TRUE)
gsub("(\\w)\\1{2,}", "\\1", s)
cyA8LSAi16nXnNec15zXnNeV15XXldeV15XXnded153XnSAuLi4uLi4uLi4gICAgICAgICDXqdec15zXnNec15XXldeV15XXlded153XndedIgpnc3ViKCIoXFxwe0hlYnJld30pXFwxezIsfSIsICJcXDEiLCBzLCBwZXJsPVRSVUUpCmdzdWIoIihcXHcpXFwxezIsfSIsICJcXDEiLCBzKQ==