List of lists to data frame?

I would like to make the following faster:

? ? ? ?df <- NULL
? ? ? ?for(i in 1:length(s))
? ? ? ?{
? ? ? ? ? ? ? ?df <- rbind(df, cbind(names(s[i]), time(s[[i]]$series),
as.vector(s[[i]]$series), s[[i]]$category))
? ? ? ?}
? ? ? ?names(df) <- c("name", "time", "value", "category")
? ? ? ?return(df)

The s object is a list of lists. It is constructed like:

s[["object"]] <- list(. . . . . .)

where "object" would be the name associated with this list s[[i]]$series
is a 'ts' object and s[[i]]$category is a name.

Constructing this list is reasonably fast but to do some more processing
on the data it would be easier if it were converted to a data frame.
Right now the above code is unacceptably slow at converting this list of
lists to a data frame. Any suggestions on how to optimize this are
welcome.

Thank you.

Kevin

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