diff --git a/conn.go b/conn.go
index d46c3b4c..3c7c413f 100644
--- a/conn.go
+++ b/conn.go
@@ -2,9 +2,6 @@ package pgx
 
 import (
 	"context"
-	"database/sql/driver"
-	"fmt"
-	"reflect"
 	"strings"
 	"time"
 
@@ -393,6 +390,7 @@ func (c *Conn) Exec(ctx context.Context, sql string, arguments ...interface{}) (
 }
 
 func (c *Conn) exec(ctx context.Context, sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error) {
+	c.eqb.Reset()
 
 	if ps, ok := c.preparedStatements[sql]; ok {
 		args, err := convertDriverValuers(arguments)
@@ -400,28 +398,24 @@ func (c *Conn) exec(ctx context.Context, sql string, arguments ...interface{}) (
 			return nil, err
 		}
 
-		paramFormats := make([]int16, len(args))
-		paramValues := make([][]byte, len(args))
 		for i := range args {
-			paramFormats[i] = chooseParameterFormatCode(c.ConnInfo, ps.ParameterOIDs[i], args[i])
-			paramValues[i], err = newencodePreparedStatementArgument(c.ConnInfo, ps.ParameterOIDs[i], args[i])
+			err = c.eqb.AppendParam(c.ConnInfo, ps.ParameterOIDs[i], args[i])
 			if err != nil {
 				return nil, err
 			}
 		}
 
-		resultFormats := make([]int16, len(ps.FieldDescriptions))
-		for i := range resultFormats {
+		for i := range ps.FieldDescriptions {
 			if dt, ok := c.ConnInfo.DataTypeForOID(pgtype.OID(ps.FieldDescriptions[i].DataTypeOID)); ok {
 				if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
-					resultFormats[i] = BinaryFormatCode
+					c.eqb.AppendResultFormat(BinaryFormatCode)
 				} else {
-					resultFormats[i] = TextFormatCode
+					c.eqb.AppendResultFormat(TextFormatCode)
 				}
 			}
 		}
 
-		result := c.pgConn.ExecPrepared(ctx, ps.Name, paramValues, paramFormats, resultFormats).Read()
+		result := c.pgConn.ExecPrepared(ctx, ps.Name, c.eqb.paramValues, c.eqb.paramFormats, c.eqb.resultFormats).Read()
 		return result.CommandTag, result.Err
 	}
 
@@ -461,87 +455,29 @@ func (c *Conn) exec(ctx context.Context, sql string, arguments ...interface{}) (
 			return nil, err
 		}
 
-		paramFormats := make([]int16, len(arguments))
-		paramValues := make([][]byte, len(arguments))
 		for i := range arguments {
-			paramFormats[i] = chooseParameterFormatCode(c.ConnInfo, ps.ParameterOIDs[i], arguments[i])
-			paramValues[i], err = newencodePreparedStatementArgument(c.ConnInfo, ps.ParameterOIDs[i], arguments[i])
+			err = c.eqb.AppendParam(c.ConnInfo, ps.ParameterOIDs[i], arguments[i])
 			if err != nil {
 				return nil, err
 			}
-
 		}
 
-		resultFormats := make([]int16, len(ps.FieldDescriptions))
-		for i := range resultFormats {
+		for i := range ps.FieldDescriptions {
 			if dt, ok := c.ConnInfo.DataTypeForOID(pgtype.OID(ps.FieldDescriptions[i].DataTypeOID)); ok {
 				if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
-					resultFormats[i] = BinaryFormatCode
+					c.eqb.AppendResultFormat(BinaryFormatCode)
 				} else {
-					resultFormats[i] = TextFormatCode
+					c.eqb.AppendResultFormat(TextFormatCode)
 				}
 			}
 		}
 
-		result := c.pgConn.ExecPrepared(ctx, psd.Name, paramValues, paramFormats, resultFormats).Read()
+		result := c.pgConn.ExecPrepared(ctx, psd.Name, c.eqb.paramValues, c.eqb.paramFormats, c.eqb.resultFormats).Read()
 		return result.CommandTag, result.Err
 	}
 
 }
 
-func newencodePreparedStatementArgument(ci *pgtype.ConnInfo, oid pgtype.OID, arg interface{}) ([]byte, error) {
-	if arg == nil {
-		return nil, nil
-	}
-
-	// TODO - don't allocate a new buf for each encoded prepared statement. The empty slice is necessary because otherwise empty strings may be encoded as []byte(nil) instead of []byte{}
-	buf := make([]byte, 0)
-
-	switch arg := arg.(type) {
-	case pgtype.BinaryEncoder:
-		return arg.EncodeBinary(ci, buf)
-	case pgtype.TextEncoder:
-		return arg.EncodeText(ci, buf)
-	case string:
-		return []byte(arg), nil
-	}
-
-	refVal := reflect.ValueOf(arg)
-
-	if refVal.Kind() == reflect.Ptr {
-		if refVal.IsNil() {
-			return nil, nil
-		}
-		arg = refVal.Elem().Interface()
-		return newencodePreparedStatementArgument(ci, oid, arg)
-	}
-
-	if dt, ok := ci.DataTypeForOID(oid); ok {
-		value := dt.Value
-		err := value.Set(arg)
-		if err != nil {
-			{
-				if arg, ok := arg.(driver.Valuer); ok {
-					v, err := callValuerValue(arg)
-					if err != nil {
-						return nil, err
-					}
-					return newencodePreparedStatementArgument(ci, oid, v)
-				}
-			}
-
-			return nil, err
-		}
-
-		return value.(pgtype.BinaryEncoder).EncodeBinary(ci, buf)
-	}
-
-	if strippedArg, ok := stripNamedType(&refVal); ok {
-		return newencodePreparedStatementArgument(ci, oid, strippedArg)
-	}
-	return nil, SerializationError(fmt.Sprintf("Cannot encode %T into oid %v - %T must implement Encoder or be converted to a string", arg, oid, arg))
-}
-
 func (c *Conn) getRows(sql string, args []interface{}) *connRows {
 	if len(c.preallocatedRows) == 0 {
 		c.preallocatedRows = make([]connRows, 64)
@@ -669,6 +605,8 @@ func (c *Conn) SendBatch(ctx context.Context, b *Batch) BatchResults {
 	batch := &pgconn.Batch{}
 
 	for _, bi := range b.items {
+		c.eqb.Reset()
+
 		var parameterOIDs []pgtype.OID
 		ps := c.preparedStatements[bi.query]
 
@@ -683,11 +621,8 @@ func (c *Conn) SendBatch(ctx context.Context, b *Batch) BatchResults {
 			return &batchResults{err: err}
 		}
 
-		paramFormats := make([]int16, len(args))
-		paramValues := make([][]byte, len(args))
 		for i := range args {
-			paramFormats[i] = chooseParameterFormatCode(c.ConnInfo, parameterOIDs[i], args[i])
-			paramValues[i], err = newencodePreparedStatementArgument(c.ConnInfo, parameterOIDs[i], args[i])
+			err = c.eqb.AppendParam(c.ConnInfo, parameterOIDs[i], args[i])
 			if err != nil {
 				return &batchResults{err: err}
 			}
@@ -697,25 +632,27 @@ func (c *Conn) SendBatch(ctx context.Context, b *Batch) BatchResults {
 		if ps != nil {
 			resultFormats := bi.resultFormatCodes
 			if resultFormats == nil {
-				resultFormats = make([]int16, len(ps.FieldDescriptions))
-				for i := range resultFormats {
+
+				for i := range ps.FieldDescriptions {
 					if dt, ok := c.ConnInfo.DataTypeForOID(pgtype.OID(ps.FieldDescriptions[i].DataTypeOID)); ok {
 						if _, ok := dt.Value.(pgtype.BinaryDecoder); ok {
-							resultFormats[i] = BinaryFormatCode
+							c.eqb.AppendResultFormat(BinaryFormatCode)
 						} else {
-							resultFormats[i] = TextFormatCode
+							c.eqb.AppendResultFormat(TextFormatCode)
 						}
 					}
 				}
+
+				resultFormats = c.eqb.resultFormats
 			}
 
-			batch.ExecPrepared(ps.Name, paramValues, paramFormats, resultFormats)
+			batch.ExecPrepared(ps.Name, c.eqb.paramValues, c.eqb.paramFormats, resultFormats)
 		} else {
 			oids := make([]uint32, len(parameterOIDs))
 			for i := 0; i < len(parameterOIDs); i++ {
 				oids[i] = uint32(parameterOIDs[i])
 			}
-			batch.ExecParams(bi.query, paramValues, oids, paramFormats, bi.resultFormatCodes)
+			batch.ExecParams(bi.query, c.eqb.paramValues, oids, c.eqb.paramFormats, bi.resultFormatCodes)
 		}
 	}