diff --git a/go.mod b/go.mod
index 95beac76..7667557f 100644
--- a/go.mod
+++ b/go.mod
@@ -21,6 +21,7 @@ require (
 	github.com/stretchr/testify v1.4.0
 	github.com/urfave/cli v1.21.0
 	golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472
+	golang.org/x/exp v0.0.0-20190829153037-c13cbed26979
 	golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297 // indirect
 	golang.org/x/sys v0.0.0-20190904005037-43c01164e931 // indirect
 	golang.org/x/text v0.3.2 // indirect
diff --git a/go.sum b/go.sum
index 0280c454..c8fd5585 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +1,5 @@
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/OneOfOne/xxhash v1.2.2 h1:KMrpdQIwFcEqXDklaen+P1axHaj9BSKzvpUUfnHldSE=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
 github.com/OneOfOne/xxhash v1.2.5 h1:zl/OfRA6nftbBK9qTohYBJ5xvw6C/oNKizR7cZGl3cI=
@@ -55,17 +56,28 @@ github.com/tscholl2/siec v0.0.0-20180721101609-21667da05937/go.mod h1:KL9+ubr1JZ
 github.com/urfave/cli v1.21.0 h1:wYSSj06510qPIzGSua9ZqsncMmWE3Zr55KBERygyrxE=
 github.com/urfave/cli v1.21.0/go.mod h1:lxDj6qX9Q6lWQxIrbrT0nwecwUtRnhVZAJjJZrVUZZQ=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190701094942-4def268fd1a4 h1:HuIa8hRrWRSrqYzx1qI49NNxhdi2PrY7gxVSq1JjLDc=
 golang.org/x/crypto v0.0.0-20190701094942-4def268fd1a4/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472 h1:Gv7RPwsi3eZ2Fgewe3CBsuOebPwO27PoXzRpJPsvSSM=
 golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
+golang.org/x/exp v0.0.0-20190829153037-c13cbed26979 h1:Agxu5KLo8o7Bb634SVDnhIfpTvxmzUwhbYAzBvXt6h4=
+golang.org/x/exp v0.0.0-20190829153037-c13cbed26979/go.mod h1:86+5VVa7VpoJ4kLfm080zCjGlMRFzhUhsZKEZO7MGek=
+golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
+golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/mobile v0.0.0-20190719004257-d2bd2a29d028/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
+golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20190724013045-ca1201d0de80/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297 h1:k7pJ2yAPLPgbskkFdhRCsA77k2fySZ1zf2zCjvQCiIM=
 golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190801041406-cbf593c0f2f3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -78,6 +90,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190816200558-6889da9d5479/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
diff --git a/src/croc/croc.go b/src/croc/croc.go
index 957d2205..24db5ec8 100644
--- a/src/croc/croc.go
+++ b/src/croc/croc.go
@@ -30,6 +30,7 @@ import (
 	"github.com/schollz/peerdiscovery"
 	"github.com/schollz/progressbar/v2"
 	"github.com/schollz/spinner"
+	"golang.org/x/exp/mmap"
 )
 
 func init() {
@@ -91,6 +92,7 @@ type Client struct {
 	firstSend bool
 
 	mutex *sync.Mutex
+	fread *mmap.ReaderAt
 	quit  chan bool
 }
 
@@ -843,6 +845,15 @@ func (c *Client) updateState() (err error) {
 		c.setBar()
 		c.TotalSent = 0
 		log.Debug("beginning sending comms")
+		pathToFile := path.Join(
+			c.FilesToTransfer[c.FilesToTransferCurrentNum].FolderSource,
+			c.FilesToTransfer[c.FilesToTransferCurrentNum].Name,
+		)
+
+		c.fread, err = mmap.Open(pathToFile)
+		if err != nil {
+			return
+		}
 		for i := 0; i < len(c.Options.RelayPorts); i++ {
 			log.Debugf("starting sending over comm %d", i)
 			go c.sendData(i)
@@ -881,6 +892,7 @@ func (c *Client) setBar() {
 }
 
 func (c *Client) receiveData(i int) {
+	log.Debugf("%d receiving data")
 	for {
 		data, err := c.conn[i+1].Receive()
 		if err != nil {
@@ -939,23 +951,30 @@ func (c *Client) sendData(i int) {
 	defer func() {
 		log.Debugf("finished with %d", i)
 	}()
-	pathToFile := path.Join(
-		c.FilesToTransfer[c.FilesToTransferCurrentNum].FolderSource,
-		c.FilesToTransfer[c.FilesToTransferCurrentNum].Name,
-	)
-	log.Debugf("opening %s to read", pathToFile)
-	f, err := os.Open(pathToFile)
-	if err != nil {
-		panic(err)
-	}
-	defer f.Close()
+	// pathToFile := path.Join(
+	// 	c.FilesToTransfer[c.FilesToTransferCurrentNum].FolderSource,
+	// 	c.FilesToTransfer[c.FilesToTransferCurrentNum].Name,
+	// )
+	// log.Debugf("opening %s to read", pathToFile)
+	// f, err := mmap.Open(pathToFile)
+	// if err != nil {
+	// 	panic(err)
+	// }
+	// defer f.Close()
 
+	var readingPos int64
 	pos := uint64(0)
 	curi := float64(0)
 	for {
 		// Read file
 		data := make([]byte, models.TCP_BUFFER_SIZE/2)
-		n, err := f.Read(data)
+		if readingPos >= int64(c.fread.Len()) {
+			break
+		}
+		log.Debug("trying to read")
+		n, err := c.fread.ReadAt(data, readingPos)
+		log.Debugf("read %d bytes", n)
+		readingPos += int64(n)
 		if err != nil {
 			if err == io.EOF {
 				break
@@ -989,7 +1008,9 @@ func (c *Client) sendData(i int) {
 					panic(err)
 				}
 
+				log.Debug("sending data")
 				err = c.conn[i+1].Send(dataToSend)
+				log.Debug("sent")
 				if err != nil {
 					panic(err)
 				}
@@ -1005,6 +1026,6 @@ func (c *Client) sendData(i int) {
 		pos += uint64(n)
 	}
 
-	time.Sleep(10 * time.Second)
+	time.Sleep(100 * time.Millisecond)
 	return
 }
diff --git a/src/croc/croc_test.go b/src/croc/croc_test.go
index 51563a6a..b66d9974 100644
--- a/src/croc/croc_test.go
+++ b/src/croc/croc_test.go
@@ -11,6 +11,7 @@ import (
 )
 
 func TestCroc(t *testing.T) {
+	log.SetLevel("trace")
 	defer os.Remove("README.md")
 	go tcp.Run("debug", "8081", "8082,8083,8084,8085")
 	go tcp.Run("debug", "8082")