Are lambdas faster to execute than normal function in Kotlin ?

Executing a function depends, may among others, on your environment, context and whether your function is suspending or not.

Very very simple answer is no.

Idk in Kotlin 1.3, but in past versions lambdas were resolved to anonymous classes by the compiler.

but in past versions lambdas were resolved to anonymous classes by the compiler

Same now

I assume that a function needs to be

inline

for faster execution. Is that right?

If this function doesn't have inline lambda in signature than it will not be faster (just nothing to optimize, it may be optimized by JIT on runtime or some optimizer on compile time)